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.
CVE-2016-10033
“—” 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.
Also known asEUVD-2020-0331 (ENISA EUVD) · GHSA-5f37-gxvh-23v6 (GitHub Security Advisories)Source: ENISA EUVD
- 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
A fix is available — apply it.
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.
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
- 99EG 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, 2026About 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-vulnerabilitiesPHPMailer 5.2.18
Patch available: PHPMailer/PHPMailer v5.2.18
https://github.com/PHPMailer/PHPMailer/releases/tag/v5.2.18[20161205] - PHPMailer Security Advisory
https://developer.joomla.org/security-centre/668-20161205-phpmailer-security-advisory.htmlPHPMailer Sendmail Argument Injection | Metasploit Module
http://www.rapid7.com/db/modules/exploit/multi/http/phpmailer_arg_injectionFull Disclosure: PHPMailer < 5.2.18 Remote Code Execution [CVE-2016-10033]
http://seclists.org/fulldisclosure/2016/Dec/78Packet Storm
http://packetstormsecurity.com/files/140350/PHPMailer-Sendmail-Argument-Injection.htmlPacket Storm
http://packetstormsecurity.com/files/140291/PHPMailer-Remote-Code-Execution.htmlPatch Availability(2)
| Vendor / Ecosystem | Fix (by version range) / Patch | Released | Source |
|---|---|---|---|
| ubuntu | libphp-phpmailer (6.2.0-2ubuntu0.1~esm1) @ jammy | 2026-11-01 | ubuntu |
| composer | phpmailer/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)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| php-phpmailer | — |
| — |
Alpine:v3.3(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| php-phpmailer | — |
| — |
Alpine:v3.4(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| php5-phpmailer | — |
| — |
Alpine:v3.5(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| php5-phpmailer | — |
| — |
Debian:11(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| libphp-phpmailer | — |
| — |
Debian:12(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| libphp-phpmailer | — |
| — |
Debian:13(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| libphp-phpmailer | — |
| — |
Debian:14(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| libphp-phpmailer | — |
| — |
Debian:7(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| libphp-phpmailer | 5.1-1, 5.1-1.1 |
| — |
Debian:8(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| libphp-phpmailer | 5.2.9+dfsg-2, 5.2.9+dfsg-2+deb8u1 |
| — |
Packagist(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| phpmailer/phpmailer | v5.2.10 ... v5.2.9 (15 versions) |
| — |
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.
- 2026-11-01 11:38 UTCVendor advisory
- 2026-11-01 11:38 UTCGHSA enrichmentGHSA-5f37-gxvh-23v6 · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-11-01 08:48 UTCGHSA enrichmentGHSA-5f37-gxvh-23v6 · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-11-01 08:48 UTCEG score recompute
- 2026-10-31 11:23 UTCEG score recompute
- 2026-10-31 11:23 UTCVendor advisory
- 2026-10-30 11:07 UTCEG score recompute
- 2026-10-30 11:07 UTCVendor advisory
- 2026-10-29 10:52 UTCEG score recompute
- 2026-10-29 10:52 UTCVendor advisory
- 2026-10-28 10:37 UTCEG score recompute
- 2026-10-28 10:37 UTCVendor advisory
- 2026-10-27 10:23 UTCEG score recompute
- 2026-10-27 10:23 UTCVendor advisory
- 2026-10-26 10:08 UTCVendor advisory
- 2026-10-25 19:50 UTCEG score recompute
- 2026-10-25 16:26 UTCEPSS rescoreEPSS 99.7% · 99th percentile
- 2026-10-25 09:52 UTCEG score recompute
- 2026-10-25 09:52 UTCVendor advisory
- 2026-10-24 09:37 UTCEG score recompute
- 2026-10-24 09:37 UTCVendor advisory
- 2026-10-23 09:22 UTCEG score recompute
- 2026-10-22 09:05 UTCEG score recompute
- 2026-10-22 09:05 UTCVendor advisory
- 2026-10-21 16:26 UTCEPSS rescoreEPSS 99.7% · 99th percentile
Show 75 moreShow fewer
- 2026-10-21 08:48 UTCEG score recompute
- 2026-10-21 08:48 UTCVendor advisory
- 2026-10-20 08:32 UTCEG score recompute
- 2026-10-20 08:32 UTCVendor advisory
- 2026-10-19 08:16 UTCEG score recompute
- 2026-10-19 08:16 UTCVendor advisory
- 2026-10-18 08:00 UTCEG score recompute
- 2026-10-17 07:44 UTCEG score recompute
- 2026-10-17 07:44 UTCVendor advisory
- 2026-10-16 07:29 UTCEG score recompute
- 2026-10-16 07:29 UTCVendor advisory
- 2026-10-15 07:14 UTCEG score recompute
- 2026-10-14 06:57 UTCEG score recompute
- 2026-10-13 06:40 UTCVendor advisory
- 2026-10-12 20:46 UTCEG score recompute
- 2026-10-12 02:42 UTCVendor advisory
- 2026-10-11 23:05 UTCVendor advisory
- 2026-10-11 19:27 UTCEG score recompute
- 2026-10-11 19:27 UTCVendor advisory
- 2026-10-11 15:49 UTCEG score recompute
- 2026-10-11 15:49 UTCVendor advisory
- 2026-10-11 12:12 UTCEG score recompute
- 2026-10-11 12:12 UTCVendor advisory
- 2026-10-11 04:53 UTCVendor advisory
- 2026-10-10 17:54 UTCVendor advisory
- 2026-10-10 14:17 UTCVendor advisory
- 2026-10-10 10:40 UTCVendor advisory
- 2026-10-10 07:01 UTCVendor advisory
- 2026-10-10 03:23 UTCVendor advisory
- 2026-10-09 23:46 UTCVendor advisory
- 2026-10-09 20:08 UTCVendor advisory
- 2026-10-09 12:52 UTCVendor advisory
- 2026-10-09 05:37 UTCVendor advisory
- 2026-10-08 22:21 UTCVendor advisory
- 2026-10-08 18:44 UTCVendor advisory
- 2026-10-08 15:06 UTCVendor advisory
- 2026-10-08 07:51 UTCVendor advisory
- 2026-10-08 00:36 UTCEG score recompute
- 2026-10-08 00:36 UTCVendor advisory
- 2026-10-07 23:40 UTCEPSS rescoreEPSS 99.7% · 99th percentile
- 2026-10-07 20:58 UTCVendor advisory
- 2026-10-07 17:21 UTCVendor advisory
- 2026-10-07 10:03 UTCVendor advisory
- 2026-10-07 06:26 UTCVendor advisory
- 2026-10-07 02:48 UTCVendor advisory
- 2026-10-06 23:10 UTCVendor advisory
- 2026-10-06 19:33 UTCVendor advisory
- 2026-10-06 15:56 UTCVendor advisory
- 2026-10-06 12:19 UTCVendor advisory
- 2026-10-06 08:42 UTCVendor advisory
- 2026-10-06 01:26 UTCVendor advisory
- 2026-10-06 01:26 UTCVendor advisory
- 2026-10-05 18:02 UTCVendor advisory
- 2026-10-05 14:24 UTCVendor advisory
- 2026-10-05 10:47 UTCVendor advisory
- 2026-10-05 07:09 UTCVendor advisory
- 2026-10-05 03:32 UTCVendor advisory
- 2026-10-04 23:54 UTCVendor advisory
- 2026-10-04 20:17 UTCVendor advisory
- 2026-10-04 16:37 UTCVendor advisory
- 2026-10-04 09:22 UTCVendor advisory
- 2026-10-04 05:44 UTCVendor advisory
- 2026-10-04 02:07 UTCVendor advisory
- 2026-10-03 22:30 UTCVendor advisory
- 2026-10-03 18:51 UTCVendor advisory
- 2026-10-03 15:13 UTCVendor advisory
- 2026-10-03 11:36 UTCVendor advisory
- 2026-10-03 07:58 UTCVendor advisory
- 2026-10-03 04:20 UTCVendor advisory
- 2026-10-03 00:42 UTCVendor advisory
- 2026-10-02 17:24 UTCVendor advisory
- 2026-10-02 13:44 UTCVendor advisory
- 2026-10-02 10:03 UTCVendor advisory
- 2026-10-02 06:25 UTCVendor advisory
- 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✓ verifiedPublished May 17, 2017
WordPress Plugin PHPMailer 4.6 - Host Header Command Injection (Metasploit)
Open source ↗ - Metasploitexploit/unix/webapp/wp_phpmailer_host_header✓ verifiedPublished May 16, 2017
WordPress PHPMailer Host Header Command Injection
Open source ↗ - Metasploitexploit/multi/http/phpmailer_arg_injection✓ verifiedPublished Jan 3, 2017
PHPMailer Sendmail Argument Injection
Open source ↗ - Exploit-DBEDB-40968✓ verifiedPublished Dec 26, 2016
PHPMailer < 5.2.18 - Remote Code Execution
Open source ↗ - Nucleihttp/cves/2016/CVE-2016-10033.yamlPublished Mar 24, 2021
WordPress PHPMailer < 5.2.18 - Remote Code Execution
Open source ↗ - GitHub PoC0x00-0x00/CVE-2016-10033Published Feb 9, 2018
PHPMailer < 5.2.18 Remote Code Execution Exploit
Open source ↗ - GitHub PoCpedro823/cve-2016-10033-45Published Nov 19, 2017
Exploits CVE-2016-10033 and CVE-2016-10045
Open source ↗ - Exploit-DBEDB-42221Published Jun 21, 2017
PHPMailer < 5.2.20 with Exim MTA - Remote Code Execution
Open source ↗ - Exploit-DBEDB-41996Published May 11, 2017
Vanilla Forums < 2.3 - Remote Code Execution
Open source ↗ - GitHub PoCGeneralTesler/CVE-2016-10033Published 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 ↗
Related CVEs(same product + same vendor + same CWE)
Same product
10 shownAlpine:v3.2:php-phpmailer · Debian:7:libphp-phpmailer · Debian:8:libphp-phpmailer
Same vendor
6 shownubuntu:USN-5956-1
Same CWE
10 shownCWE-77
- CVE-2016-10034EG 9.8EPSS p99CRITICAL
- CVE-2016-10045EG 9.8EPSS p100CRITICAL
- CVE-2016-10074EG 9.8EPSS p99CRITICAL
- CVE-2016-10107EG 9.8EPSS p96CRITICAL
- CVE-2016-10108EG 9.8EPSS p100CRITICAL
- CVE-2016-7399EG 9.8EPSS p92CRITICAL
- CVE-2015-3441EG 8.8HIGH
- CVE-2016-6656EG 7.2HIGH
- CVE-2016-1000156EG 9.8CRITICAL
- CVE-2016-6609EG 8.8HIGH
Frequently asked(6)
What is CVE-2016-10033?
When was CVE-2016-10033 made public?
Is CVE-2016-10033 actively exploited?
What is the CVSS score of CVE-2016-10033?
Which products are affected by CVE-2016-10033?
How do I remediate CVE-2016-10033?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2016-10033
Is Your Infrastructure Affected by CVE-2016-10033?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.