CVE-2016-5771

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

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, ghsa, nvd
Elevated
9.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 15%CVSS: 9.8Exploit: NoneExposed: 0

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
9.8(medium)
EG Risk
65(Track*)
EG Risk 65/100SSVC: Track*

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity98% × 45%
Exploitation40% × 40%
Automatability30% × 15%
Action: Watch closely — could escalate to Attend.
EPSS
96.5%
KEV
Not listed

Published

August 7, 2016

Last Modified

May 6, 2026

Advisory Details (7)

Auto-updated May 8, 2026
No patch confirmed yet.
generic

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

https://bugs.php.net/bug.php?id=72433
generic
http://www.securityfocus.com/bid/91401
generic

oss-security - Re: CVE for PHP 5.5.37 issues

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

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

http://www.debian.org/security/2016/dsa-3618
generic
http://rhn.redhat.com/errata/RHSA-2016-2750.html
generic

PHP: PHP 5 ChangeLog

http://php.net/ChangeLog-5.php
generic

Fixed ##72433: Use After Free Vulnerability in PHP's GC algorithm and… · php/php-src@3f627e5 · GitHub

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

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 / EcosystemFixed in / PatchReleasedSource
ubuntuphp7.0-zip (7.0.8-0ubuntu0.16.04.2) @ xenial2026-05-20ubuntu
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.

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 12× in last 7d / 40× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. 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. Most recent first.

Showing the most recent 100 of 109 total refreshes for this CVE.

  1. 2026-07-23 01:23 UTCEG score recompute
  2. 2026-07-22 22:03 UTCEG score recompute
  3. 2026-07-22 14:04 UTCEPSS rescore
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  49. 2026-05-30 20:53 UTCOSV refresh
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  63. 2026-05-20 08:24 UTCVendor advisory
  64. 2026-05-20 08:24 UTCGHSA enrichment
  65. 2026-05-20 04:28 UTCVendor advisory
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  69. 2026-05-19 20:31 UTCVendor advisory
  70. 2026-05-19 20:31 UTCGHSA enrichment
  71. 2026-05-19 16:25 UTCVendor advisory
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  73. 2026-05-19 12:29 UTCVendor advisory
  74. 2026-05-19 12:29 UTCGHSA enrichment
  75. 2026-05-19 08:22 UTCVendor advisory

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Frequently asked(5)

What is CVE-2016-5771?
CVE-2016-5771 is a critical vulnerability 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 disclosed?
CVE-2016-5771 was first published in the National Vulnerability Database on August 7, 2016, with the most recent update on May 6, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2016-5771 actively exploited?
CVE-2016-5771 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 96.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
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?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2016-5771, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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