CVE-2016-10033

CRITICALNVD 9.89.8
EchelonGraph scoreHIGH confidence

“—” beside the score: it is equal to NVD's CVSS score.

Score elevated to 9.8 because this CVE is listed on the CISA Known Exploited Vulnerabilities catalog (added 2025-07-07), indicating real-world exploitation has been confirmed by US federal agencies. NVD baseline CVSS 9.8 retained for reference. Confidence: HIGH.

Triggered by: CISA KEV (actively exploited)
Sources: CISA Known Exploited Vulnerabilities catalog, EPSS, GitHub Security Advisory, NVD CVSS v3
Trending — 3 sources updated this weekExploited in the wild

Also known asEUVD-2020-0331 (ENISA EUVD) · GHSA-5f37-gxvh-23v6 (GitHub Security Advisories)Source: ENISA EUVD

9.8EG
EchelonGraph verdictPatch nowTreat as an emergency — this is being exploited.
  • 300 internet-facing services (distinct ip:port) on record running an affected version — derived from Shodan data (© Shodan); a patched service can stay counted while its port stays open
  • Actively exploited in the wild (CISA-KEV) — the reason this is sooner than the SSVC decision on this page at low mission impact
CISA-KEV: ExploitedEPSS PROB: 99.7%CVSS: 9.8Exploit: Metasploit · Exploit-DB (verified) · other public PoCExposed services: 300

A fix is available — apply it.

The mailSend function in the isMail transport in PHPMailer before 5.2.18 might allow remote attackers to pass extra parameters to the mail command and consequently execute arbitrary code via a \" (backslash double quote) in a crafted Sender property.

Internet exposure · derived from Shodan data

300 internet-facing services (distinct ip:port) on record running a version that maps to CVE-2016-10033, in our KEV-Exposure radar’s Shodan-derived sample.

across 34 countries (United States, Germany, United Kingdom, Netherlands, Singapore)top: wordpress
See the KEV-Exposure radar →Derived from Shodan data. Shodan data is owned by Shodan, which holds its copyright (© Shodan). EchelonGraph claims no ownership of it or copyright in it. Aggregate, host-redacted.

How it counts: every 12 hours, when Shodan query credits allow, the radar runs one Shodan query per tracked product, reads up to 100 ip:port services per query, and keeps a service when its banner version matches a CISA-KEV or high-EPSS CVE; a service is dropped when neither a search nor a Shodan InternetDB port re-check has refreshed it for 21 days. A re-check that finds the port still listed by Shodan InternetDB refreshes the service without re-reading the banner, so a patched service can stay counted while its port stays open. A count is a banner-version inference over a sample, not an exploit test and not an internet-wide census, and the unit is a service, not a machine: a machine answering on two ports counts twice.

CVSS v3
9.8
EG Score
9.8CRITICALhigh confidence
EG Risk
99
EG Risk 99/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity98% × 45%
Impact severity (EG Severity): CVSS 9.8 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation100% × 40%
Fixed at 100% for a CISA KEV listing: EchelonGraph's rule.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Attend at low mission impact; Act at medium or high.
Exploitation active (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it sooner than your standard update timelines at low mission impact and as soon as possible at medium or high.
EPSS PROB
99.7%
EPSS %ILE
99th
KEV
⚠ Exploited

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (9.8): severity, escalated by confirmed exploitation. This CVE's 9.8 is its impact severity (EG Severity), not escalated.

EG Severity
9.8 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
99.7% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-31). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
CISA KEV and EG-KEV Tier 1 (exploited in the wild)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Act at medium mission impactAttend at low mission impact; Act at medium or high.CISA BOD 26-04: 3 days & forensic triage if the affected system is publicly exposed; 3 days & forensic triage if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Attend at low mission impact; Act at medium or high.

A fix is available. Apply it sooner than your standard update timelines at low mission impact and as soon as possible at medium or high.

Exploitation active (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)3 days & forensic triage if the affected system is publicly exposed; 3 days & forensic triage if it is not.

The score's inputs: In CISA KEV yes (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

CISA required action“Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.”

Quoted verbatim from CISA's Known Exploited Vulnerabilities catalog. CISA directs it at US federal civilian executive branch agencies under Binding Operational Directive (BOD) 26-04, which replaced BOD 22-01 on 10 June 2026; it is not EchelonGraph's advice. CISA's notes: https://github.com/PHPMailer/PHPMailer/releases/tag/v5.2.18 · https://github.com/advisories/GHSA-5f37-gxvh-23v6 · https://nvd.nist.gov/vuln/detail/CVE-2016-10033

Published

December 30, 2016

Last Modified

June 17, 2026

Advisory Details (10)

Auto-updated Oct 28, 2026
⚠️ Actively exploited (CISA KEV, CISA Vulnrichment). Patch available. Sources: github_release.
Web page

About the CVE 2016 10033 and CVE 2016 10045 vulnerabilities · PHPMailer/PHPMailer Wiki · GitHub

https://github.com/PHPMailer/PHPMailer/wiki/About-the-CVE-2016-10033-and-CVE-2016-10045-vulnerabilities
GitHub release Patch Available

PHPMailer 5.2.18

Patch available: PHPMailer/PHPMailer v5.2.18

https://github.com/PHPMailer/PHPMailer/releases/tag/v5.2.18
Web page

PSIRT.COM — Product Security Incident Response Team

http://www.securityfocus.com/bid/95108
Web page

PHPMailer Sendmail Argument Injection | Metasploit Module

http://www.rapid7.com/db/modules/exploit/multi/http/phpmailer_arg_injection
Web page

Full Disclosure: PHPMailer < 5.2.18 Remote Code Execution [CVE-2016-10033]

http://seclists.org/fulldisclosure/2016/Dec/78

Patch Availability(2)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntulibphp-phpmailer (6.2.0-2ubuntu0.1~esm1) @ jammy2026-11-01ubuntu
composerphpmailer/phpmailer @ 5.2.18 (fixes >= 5.0.0, < 5.2.18)—ghsa

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(11 across 11 ecosystems)
Alpine:v3.2(1)
PackageVulnerable rangeFix by version rangeDependents
php-phpmailer—
  • every version up to 5.2.4-r0: fixed in 5.2.4-r0
—
Alpine:v3.3(1)
PackageVulnerable rangeFix by version rangeDependents
php-phpmailer—
  • every version up to 5.2.4-r0: fixed in 5.2.4-r0
—
Alpine:v3.4(1)
PackageVulnerable rangeFix by version rangeDependents
php5-phpmailer—
  • every version up to 5.2.0-r1: fixed in 5.2.0-r1
—
Alpine:v3.5(1)
PackageVulnerable rangeFix by version rangeDependents
php5-phpmailer—
  • every version up to 5.2.4-r1: fixed in 5.2.4-r1
—
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
libphp-phpmailer—
  • every version up to 5.2.14+dfsg-2.1: fixed in 5.2.14+dfsg-2.1
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
libphp-phpmailer—
  • every version up to 5.2.14+dfsg-2.1: fixed in 5.2.14+dfsg-2.1
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
libphp-phpmailer—
  • every version up to 5.2.14+dfsg-2.1: fixed in 5.2.14+dfsg-2.1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
libphp-phpmailer—
  • every version up to 5.2.14+dfsg-2.1: fixed in 5.2.14+dfsg-2.1
—
Debian:7(1)
PackageVulnerable rangeFix by version rangeDependents
libphp-phpmailer5.1-1, 5.1-1.1
  • every version up to 5.1-1.2: fixed in 5.1-1.2
—
Debian:8(1)
PackageVulnerable rangeFix by version rangeDependents
libphp-phpmailer5.2.9+dfsg-2, 5.2.9+dfsg-2+deb8u1
  • every version up to 5.2.9+dfsg-2+deb8u2: fixed in 5.2.9+dfsg-2+deb8u2
—
Packagist(1)
PackageVulnerable rangeFix by version rangeDependents
phpmailer/phpmailerv5.2.10 ... v5.2.9 (15 versions)
  • 5.0.0 up to 5.2.18: fixed in 5.2.18
—

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 15× in last 7d / 93× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 100 of 817 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 717 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-01 11:38 UTCVendor advisory
  2. 2026-11-01 11:38 UTCGHSA enrichmentGHSA-5f37-gxvh-23v6 · GitHub severity CRITICAL · GitHub CVSS 9.8
  3. 2026-11-01 08:48 UTCGHSA enrichmentGHSA-5f37-gxvh-23v6 · GitHub severity CRITICAL · GitHub CVSS 9.8
  4. 2026-11-01 08:48 UTCEG score recompute
  5. 2026-10-31 11:23 UTCEG score recompute
  6. 2026-10-31 11:23 UTCVendor advisory
  7. 2026-10-30 11:07 UTCEG score recompute
  8. 2026-10-30 11:07 UTCVendor advisory
  9. 2026-10-29 10:52 UTCEG score recompute
  10. 2026-10-29 10:52 UTCVendor advisory
  11. 2026-10-28 10:37 UTCEG score recompute
  12. 2026-10-28 10:37 UTCVendor advisory
  13. 2026-10-27 10:23 UTCEG score recompute
  14. 2026-10-27 10:23 UTCVendor advisory
  15. 2026-10-26 10:08 UTCVendor advisory
  16. 2026-10-25 19:50 UTCEG score recompute
  17. 2026-10-25 16:26 UTCEPSS rescoreEPSS 99.7% · 99th percentile
  18. 2026-10-25 09:52 UTCEG score recompute
  19. 2026-10-25 09:52 UTCVendor advisory
  20. 2026-10-24 09:37 UTCEG score recompute
  21. 2026-10-24 09:37 UTCVendor advisory
  22. 2026-10-23 09:22 UTCEG score recompute
  23. 2026-10-22 09:05 UTCEG score recompute
  24. 2026-10-22 09:05 UTCVendor advisory
  25. 2026-10-21 16:26 UTCEPSS rescoreEPSS 99.7% · 99th percentile
Show 75 more
  1. 2026-10-21 08:48 UTCEG score recompute
  2. 2026-10-21 08:48 UTCVendor advisory
  3. 2026-10-20 08:32 UTCEG score recompute
  4. 2026-10-20 08:32 UTCVendor advisory
  5. 2026-10-19 08:16 UTCEG score recompute
  6. 2026-10-19 08:16 UTCVendor advisory
  7. 2026-10-18 08:00 UTCEG score recompute
  8. 2026-10-17 07:44 UTCEG score recompute
  9. 2026-10-17 07:44 UTCVendor advisory
  10. 2026-10-16 07:29 UTCEG score recompute
  11. 2026-10-16 07:29 UTCVendor advisory
  12. 2026-10-15 07:14 UTCEG score recompute
  13. 2026-10-14 06:57 UTCEG score recompute
  14. 2026-10-13 06:40 UTCVendor advisory
  15. 2026-10-12 20:46 UTCEG score recompute
  16. 2026-10-12 02:42 UTCVendor advisory
  17. 2026-10-11 23:05 UTCVendor advisory
  18. 2026-10-11 19:27 UTCEG score recompute
  19. 2026-10-11 19:27 UTCVendor advisory
  20. 2026-10-11 15:49 UTCEG score recompute
  21. 2026-10-11 15:49 UTCVendor advisory
  22. 2026-10-11 12:12 UTCEG score recompute
  23. 2026-10-11 12:12 UTCVendor advisory
  24. 2026-10-11 04:53 UTCVendor advisory
  25. 2026-10-10 17:54 UTCVendor advisory
  26. 2026-10-10 14:17 UTCVendor advisory
  27. 2026-10-10 10:40 UTCVendor advisory
  28. 2026-10-10 07:01 UTCVendor advisory
  29. 2026-10-10 03:23 UTCVendor advisory
  30. 2026-10-09 23:46 UTCVendor advisory
  31. 2026-10-09 20:08 UTCVendor advisory
  32. 2026-10-09 12:52 UTCVendor advisory
  33. 2026-10-09 05:37 UTCVendor advisory
  34. 2026-10-08 22:21 UTCVendor advisory
  35. 2026-10-08 18:44 UTCVendor advisory
  36. 2026-10-08 15:06 UTCVendor advisory
  37. 2026-10-08 07:51 UTCVendor advisory
  38. 2026-10-08 00:36 UTCEG score recompute
  39. 2026-10-08 00:36 UTCVendor advisory
  40. 2026-10-07 23:40 UTCEPSS rescoreEPSS 99.7% · 99th percentile
  41. 2026-10-07 20:58 UTCVendor advisory
  42. 2026-10-07 17:21 UTCVendor advisory
  43. 2026-10-07 10:03 UTCVendor advisory
  44. 2026-10-07 06:26 UTCVendor advisory
  45. 2026-10-07 02:48 UTCVendor advisory
  46. 2026-10-06 23:10 UTCVendor advisory
  47. 2026-10-06 19:33 UTCVendor advisory
  48. 2026-10-06 15:56 UTCVendor advisory
  49. 2026-10-06 12:19 UTCVendor advisory
  50. 2026-10-06 08:42 UTCVendor advisory
  51. 2026-10-06 01:26 UTCVendor advisory
  52. 2026-10-06 01:26 UTCVendor advisory
  53. 2026-10-05 18:02 UTCVendor advisory
  54. 2026-10-05 14:24 UTCVendor advisory
  55. 2026-10-05 10:47 UTCVendor advisory
  56. 2026-10-05 07:09 UTCVendor advisory
  57. 2026-10-05 03:32 UTCVendor advisory
  58. 2026-10-04 23:54 UTCVendor advisory
  59. 2026-10-04 20:17 UTCVendor advisory
  60. 2026-10-04 16:37 UTCVendor advisory
  61. 2026-10-04 09:22 UTCVendor advisory
  62. 2026-10-04 05:44 UTCVendor advisory
  63. 2026-10-04 02:07 UTCVendor advisory
  64. 2026-10-03 22:30 UTCVendor advisory
  65. 2026-10-03 18:51 UTCVendor advisory
  66. 2026-10-03 15:13 UTCVendor advisory
  67. 2026-10-03 11:36 UTCVendor advisory
  68. 2026-10-03 07:58 UTCVendor advisory
  69. 2026-10-03 04:20 UTCVendor advisory
  70. 2026-10-03 00:42 UTCVendor advisory
  71. 2026-10-02 17:24 UTCVendor advisory
  72. 2026-10-02 13:44 UTCVendor advisory
  73. 2026-10-02 10:03 UTCVendor advisory
  74. 2026-10-02 06:25 UTCVendor advisory
  75. 2026-10-02 02:48 UTCVendor advisory

Publicly available exploits

(17 references, 10 shown)

Public exploit code is referenced for this CVE (2 Metasploit modules, 9 Exploit-DB entries, 5 GitHub PoCs), as is 1 Nuclei detection template. A detection template checks whether a system is affected; it is not necessarily exploit code. Defenders should treat patch urgency accordingly.

  • Exploit-DBEDB-42024✓ verified
    Published May 17, 2017

    WordPress Plugin PHPMailer 4.6 - Host Header Command Injection (Metasploit)

    Open source ↗
  • Metasploitexploit/unix/webapp/wp_phpmailer_host_header✓ verified
    Published May 16, 2017

    WordPress PHPMailer Host Header Command Injection

    Open source ↗
  • Metasploitexploit/multi/http/phpmailer_arg_injection✓ verified
    Published Jan 3, 2017

    PHPMailer Sendmail Argument Injection

    Open source ↗
  • Exploit-DBEDB-40968✓ verified
    Published Dec 26, 2016

    PHPMailer < 5.2.18 - Remote Code Execution

    Open source ↗
  • Nucleihttp/cves/2016/CVE-2016-10033.yaml
    Published Mar 24, 2021

    WordPress PHPMailer < 5.2.18 - Remote Code Execution

    Open source ↗
  • GitHub PoC0x00-0x00/CVE-2016-10033
    Published Feb 9, 2018

    PHPMailer < 5.2.18 Remote Code Execution Exploit

    Open source ↗
  • GitHub PoCpedro823/cve-2016-10033-45
    Published Nov 19, 2017

    Exploits CVE-2016-10033 and CVE-2016-10045

    Open source ↗
  • Exploit-DBEDB-42221
    Published Jun 21, 2017

    PHPMailer < 5.2.20 with Exim MTA - Remote Code Execution

    Open source ↗
  • Exploit-DBEDB-41996
    Published May 11, 2017

    Vanilla Forums < 2.3 - Remote Code Execution

    Open source ↗
  • GitHub PoCGeneralTesler/CVE-2016-10033
    Published May 10, 2017

    RCE against WordPress 4.6; Python port of https://exploitbox.io/vuln/WordPress-Exploit-4-6-RCE-CODE-EXEC-CVE-2016-10033.html

    Open source ↗

Frequently asked(6)

What is CVE-2016-10033?
CVE-2016-10033 is a critical-severity vulnerability; its CVE record was published on December 30, 2016. The mailSend function in the isMail transport in PHPMailer before 5.2.18 might allow remote attackers to pass extra parameters to the mail command and consequently execute arbitrary code via a \" (backslash double quote) in a crafted Sender property.
When was CVE-2016-10033 made public?
CVE-2016-10033 was made public on December 25, 2016: that is the date its CVE record's CNA, MITRE Corporation, gives for when the vulnerability was made public. The CVE record itself was published on December 30, 2016. EchelonGraph's copy of the record carries a last-modified date of June 17, 2026; the record at its source may have been updated since.
Is CVE-2016-10033 actively exploited?
Yes. CISA added CVE-2016-10033 to the Known Exploited Vulnerabilities catalog on July 7, 2025, affecting PHP PHPMailer. KEV listing indicates confirmed exploitation in the wild; this CVE warrants immediate attention. A fix is available. Apply it.
What is the CVSS score of CVE-2016-10033?
CVE-2016-10033 has a CVSS v3 base score of 9.8 (NVD).
Which products are affected by CVE-2016-10033?
CVE-2016-10033 affects PHP PHPMailer. The affected packages EchelonGraph has on record, with version ranges, are listed in the Affected Packages section of this page.
How do I remediate CVE-2016-10033?
A fix for CVE-2016-10033 is available: update to the fixed version the vendor names in its advisory.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2016-10033

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