CVE-2016-5771

CRITICALNVD 9.89.8
EchelonGraph scoreMEDIUM confidence

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

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2022-05-14. NVD baseline CVSS 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3
Trending — 5 sources updated this weekElevated

Also known asEUVD-2016-6706 (ENISA EUVD) · GHSA-pxh8-vqh4-j2qq (GitHub Security Advisories)Source: ENISA EUVD

9.8EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 15%CVSS: 9.8Exploit: No code on recordExposed services: Not assessed

A fix is available — apply it.

spl_array.c in the SPL extension in PHP before 5.5.37 and 5.6.x before 5.6.23 improperly interacts with the unserialize implementation and garbage collection, which allows remote attackers to execute arbitrary code or cause a denial of service (use-after-free and application crash) via crafted serialized data.

CVSS v3
9.8
EG Score
9.8CRITICALmedium confidence
EG Risk
60
EG Risk 60/100

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.
Exploitation40% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.
Automatability0% × 15%
CISA's BOD 26-04 default: no one has published Automatable for this CVE, and CISA treats it as “no” for a CVE not in KEV.
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).
Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from 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 within your standard update timelines.
EPSS PROB
15%
EPSS %ILE
96th
KEV
Not listed

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
15% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-01). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade 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)Track at low or medium mission impact; Track* at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines.

Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from 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)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). Where an input reads “CISA's BOD 26-04 default”, no one has published it for this CVE, and CISA's implementation guidance says: “If “Automatable” and “Technical Impact” information items about a CVE ID are not available and the CVE ID is not in the KEV Catalog, CISA will treat its values as “no” and “total,” respectively, until CISA or a third party provides metadata about the CVE ID. CISA will always provide the Vulnrichment data for a CVE ID listed in the KEV Catalog.” 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

Published

August 7, 2016

Last Modified

June 17, 2026

Advisory Details (7)

Auto-updated Oct 7, 2026
Patch available. Sources: github_commit.
Web page

PHP :: Sec Bug #72433 :: Use After Free Vulnerability in PHP's GC algorithm and unserialize

https://bugs.php.net/bug.php?id=72433
Web page

oss-security - Re: CVE for PHP 5.5.37 issues

http://www.openwall.com/lists/oss-security/2016/06/23/4
Web page

[SECURITY] [DSA 3618-1] php5 security update

http://www.debian.org/security/2016/dsa-3618
Web page

PHP: PHP 5 ChangeLog

http://php.net/ChangeLog-5.php
GitHub commit Patch Available

commit 3f627e580acf (php/php-src)

Patch available: php/php-src php-8.5.1 (contains commit 3f627e580acf)

http://github.com/php/php-src/commit/3f627e580acfdaf0595ae3b115b8bec677f203ee?w=1
Web page

CVE-2016-5771 - PSIRT.COM

http://www.securityfocus.com/bid/91401

Vendor Advisories for CVE-2016-5771(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(2)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntuphp7.0-zip (7.0.8-0ubuntu0.16.04.2) @ xenial2026-11-01ubuntu
redhatrh-php56-php-pear-1:1.9.5-4.el72016-11-15redhat

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

(2 across 2 ecosystems)
Debian:7(1)
PackageVulnerable rangeFix by version rangeDependents
php55.4.11-1 ... 5.4.9-4 (39 versions)
  • every version up to 5.4.45-0+deb7u5: fixed in 5.4.45-0+deb7u5
—
Debian:8(1)
PackageVulnerable rangeFix by version rangeDependents
php55.6.11+dfsg-1 ... 5.6.9+dfsg-1 (30 versions)
  • every version up to 5.6.23+dfsg-0+deb8u1: fixed in 5.6.23+dfsg-0+deb8u1
—

Weakness Classification(1)

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

Additional Vendor Advisories

(1)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 31× in last 7d / 97× 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 99 of 257 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. 1 repeat row among the latest 100 is merged into the row it repeats. The 158 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-02 11:55 UTCOSV refresh
  2. 2026-11-02 08:11 UTCEG score recompute
  3. 2026-11-02 08:11 UTCVendor advisory
  4. 2026-11-02 08:11 UTCGHSA enrichmentGHSA-pxh8-vqh4-j2qq · GitHub severity CRITICAL · GitHub CVSS 9.8
  5. 2026-11-01 16:27 UTCEPSS rescoreEPSS 15% · 96th percentile
  6. 2026-11-01 09:55 UTCEG score recompute
  7. 2026-11-01 09:55 UTCVendor advisory
  8. 2026-11-01 09:55 UTCGHSA enrichmentGHSA-pxh8-vqh4-j2qq · GitHub severity CRITICAL · GitHub CVSS 9.8
  9. 2026-10-31 16:27 UTCEPSS rescoreEPSS 15% · 96th percentile
  10. 2026-10-31 11:38 UTCEG score recompute
  11. 2026-10-31 11:38 UTCVendor advisory
  12. 2026-10-31 11:38 UTCGHSA enrichmentGHSA-pxh8-vqh4-j2qq · GitHub severity CRITICAL · GitHub CVSS 9.8
  13. 2026-10-30 16:27 UTCEPSS rescoreEPSS 15% · 96th percentile
  14. 2026-10-30 13:21 UTCEG score recompute
  15. 2026-10-30 13:21 UTCVendor advisory
  16. 2026-10-30 13:21 UTCGHSA enrichmentGHSA-pxh8-vqh4-j2qq · GitHub severity CRITICAL · GitHub CVSS 9.8
  17. 2026-10-29 16:27 UTCEPSS rescoreEPSS 15% · 96th percentile
  18. 2026-10-29 15:06 UTCVendor advisory
  19. 2026-10-29 15:05 UTCGHSA enrichmentGHSA-pxh8-vqh4-j2qq · GitHub severity CRITICAL · GitHub CVSS 9.8
  20. 2026-10-28 16:50 UTCEG score recompute
  21. 2026-10-28 16:50 UTCVendor advisory
  22. 2026-10-28 16:49 UTCGHSA enrichmentGHSA-pxh8-vqh4-j2qq · GitHub severity CRITICAL · GitHub CVSS 9.8
  23. 2026-10-28 16:26 UTCEPSS rescoreEPSS 15% · 96th percentile
  24. 2026-10-27 18:28 UTCEG score recompute
  25. 2026-10-27 18:28 UTCVendor advisory
Show 74 more
  1. 2026-10-27 18:28 UTCGHSA enrichmentGHSA-pxh8-vqh4-j2qq · GitHub severity CRITICAL · GitHub CVSS 9.8
  2. 2026-10-27 16:26 UTCEPSS rescoreEPSS 15% · 96th percentile
  3. 2026-10-26 20:11 UTCEG score recompute
  4. 2026-10-26 20:11 UTCVendor advisory
  5. 2026-10-26 20:10 UTCGHSA enrichmentGHSA-pxh8-vqh4-j2qq · GitHub severity CRITICAL · GitHub CVSS 9.8
  6. 2026-10-26 16:26 UTCEPSS rescoreEPSS 15% · 96th percentile
  7. 2026-10-25 19:56 UTCVendor advisory
  8. 2026-10-25 19:56 UTCGHSA enrichmentGHSA-pxh8-vqh4-j2qq · GitHub severity CRITICAL · GitHub CVSS 9.8
  9. 2026-10-25 19:45 UTCEG score recompute
  10. 2026-10-25 16:27 UTCEPSS rescoreEPSS 15% · 96th percentile
  11. 2026-10-24 21:38 UTCEG score recompute
  12. 2026-10-24 21:38 UTCVendor advisory
  13. 2026-10-24 21:38 UTCGHSA enrichmentGHSA-pxh8-vqh4-j2qq · GitHub severity CRITICAL · GitHub CVSS 9.8
  14. 2026-10-24 16:27 UTCEPSS rescoreEPSS 15% · 96th percentile
  15. 2026-10-23 23:23 UTCEG score recompute
  16. 2026-10-23 23:23 UTCVendor advisory
  17. 2026-10-23 23:22 UTCGHSA enrichmentGHSA-pxh8-vqh4-j2qq · GitHub severity CRITICAL · GitHub CVSS 9.8
  18. 2026-10-23 16:26 UTCEPSS rescoreEPSS 15% · 96th percentile
  19. 2026-10-23 00:53 UTCEG score recompute
  20. 2026-10-23 00:53 UTCVendor advisory
  21. 2026-10-23 00:53 UTCGHSA enrichmentGHSA-pxh8-vqh4-j2qq · GitHub severity CRITICAL · GitHub CVSS 9.8
  22. 2026-10-22 16:27 UTCEPSS rescoreEPSS 15% · 96th percentile
  23. 2026-10-22 02:07 UTCEG score recompute
  24. 2026-10-22 02:07 UTCVendor advisory
  25. 2026-10-22 02:07 UTCGHSA enrichmentGHSA-pxh8-vqh4-j2qq · GitHub severity CRITICAL · GitHub CVSS 9.8
  26. 2026-10-21 16:27 UTCEPSS rescoreEPSS 15% · 96th percentile
  27. 2026-10-21 03:47 UTCEG score recompute
  28. 2026-10-21 03:47 UTCVendor advisory
  29. 2026-10-21 03:47 UTCGHSA enrichmentGHSA-pxh8-vqh4-j2qq · GitHub severity CRITICAL · GitHub CVSS 9.8
  30. 2026-10-20 16:27 UTCEPSS rescoreEPSS 15% · 96th percentile
  31. 2026-10-20 05:27 UTCEG score recompute
  32. 2026-10-20 05:27 UTCVendor advisory
  33. 2026-10-20 05:27 UTCGHSA enrichmentGHSA-pxh8-vqh4-j2qq · GitHub severity CRITICAL · GitHub CVSS 9.8
  34. 2026-10-19 16:26 UTCEPSS rescoreEPSS 15% · 96th percentile
  35. 2026-10-19 06:52 UTCEG score recompute
  36. 2026-10-19 06:52 UTCVendor advisory
  37. 2026-10-19 06:51 UTCGHSA enrichmentGHSA-pxh8-vqh4-j2qq · GitHub severity CRITICAL · GitHub CVSS 9.8
  38. 2026-10-18 16:26 UTCEPSS rescoreEPSS 15% · 96th percentile
  39. 2026-10-18 08:33 UTCEG score recompute
  40. 2026-10-18 08:33 UTCVendor advisory
  41. 2026-10-18 08:33 UTCGHSA enrichmentGHSA-pxh8-vqh4-j2qq · GitHub severity CRITICAL · GitHub CVSS 9.8
  42. 2026-10-17 16:27 UTCEPSS rescoreEPSS 15% · 96th percentile
  43. 2026-10-17 10:15 UTCEG score recompute
  44. 2026-10-17 10:15 UTCVendor advisory
  45. 2026-10-17 10:14 UTCGHSA enrichmentGHSA-pxh8-vqh4-j2qq · GitHub severity CRITICAL · GitHub CVSS 9.8
  46. 2026-10-16 16:28 UTCEPSS rescoreEPSS 15% · 96th percentile
  47. 2026-10-16 11:55 UTCEG score recompute
  48. 2026-10-16 11:55 UTCVendor advisory
  49. 2026-10-16 11:54 UTCGHSA enrichmentGHSA-pxh8-vqh4-j2qq · GitHub severity CRITICAL · GitHub CVSS 9.8
  50. 2026-10-15 16:26 UTCEPSS rescoreEPSS 15% · 96th percentile
  51. 2026-10-15 13:05 UTCEG score recompute
  52. 2026-10-15 13:05 UTCVendor advisory
  53. 2026-10-15 13:05 UTCGHSA enrichmentGHSA-pxh8-vqh4-j2qq · GitHub severity CRITICAL · GitHub CVSS 9.8
  54. 2026-10-14 16:27 UTCEPSS rescoreEPSS 15% · 96th percentile
  55. 2026-10-14 08:15 UTCEG score recompute
  56. 2026-10-14 08:15 UTCVendor advisory
  57. 2026-10-14 08:15 UTCGHSA enrichmentGHSA-pxh8-vqh4-j2qq · GitHub severity CRITICAL · GitHub CVSS 9.8
  58. 2026-10-13 16:27 UTCEPSS rescoreEPSS 15% · 96th percentile
  59. 2026-10-13 03:28 UTCVendor advisory
  60. 2026-10-13 03:28 UTCGHSA enrichmentGHSA-pxh8-vqh4-j2qq · GitHub severity CRITICAL · GitHub CVSS 9.8
  61. 2026-10-12 20:41 UTCEG score recompute
  62. 2026-10-12 16:28 UTCEPSS rescoreEPSS 15% · 96th percentile
  63. 2026-10-12 01:05 UTCEG score recompute
  64. 2026-10-11 13:40 UTCEPSS rescoreEPSS 15% · 96th percentile
  65. 2026-10-10 19:55 UTCEPSS rescoreEPSS 15% · 96th percentile
  66. 2026-10-09 20:01 UTCEPSS rescoreEPSS 15% · 96th percentile
  67. 2026-10-08 16:35 UTCEPSS rescoreEPSS 15% · 96th percentile
  68. 2026-10-07 23:40 UTCEPSS rescoreEPSS 15% · 96th percentile
  69. 2026-10-06 15:11 UTCEPSS rescoreEPSS 15% · 96th percentile
  70. 2026-10-05 17:38 UTCEPSS rescoreEPSS 15% · 96th percentile
  71. 2026-10-04 01:44 UTCOSV refresh
  72. 2026-10-03 14:21 UTCEPSS rescoreEPSS 15% · 96th percentile
  73. 2026-09-30 14:58 UTCEPSS rescoreEPSS 15% · 96th percentile
  74. 2026-09-30 09:14 UTCEG score recompute

Frequently asked(5)

What is CVE-2016-5771?
CVE-2016-5771 is a critical-severity vulnerability; its CVE record was published on August 7, 2016. spl_array.c in the SPL extension in PHP before 5.5.37 and 5.6.x before 5.6.23 improperly interacts with the unserialize implementation and garbage collection, which allows remote attackers to execute arbitrary code or cause a denial of service (use-after-free and application crash) via crafted…
When was CVE-2016-5771 made public?
CVE-2016-5771 was made public on June 23, 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 August 7, 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-2016-5771 actively exploited?
CVE-2016-5771 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 15% probability of exploitation in the next 30 days (96th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2016-5771?
CVE-2016-5771 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2016-5771?
A fix for CVE-2016-5771 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2016-5771 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2016-5771

Explore →

Is Your Infrastructure Affected by CVE-2016-5771?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.