No exploitation reportedFix available

CVE-2016-5771

Q: Is CVE-2016-5771 actively exploited?

Active exploitation of CVE-2016-5771 has not been confirmed. Its EPSS score was 15.5% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2016-5771?

CVE-2016-5771 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

No exploitation reported by the sources we read.

Published2016-08-07
Fixed in7.0.8 · 5.6.23 · 5.5.37
WeaknessCWE-416

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

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.

Timeline

dates in UTC

2016-08-0710:59CVE publishedNVD
2026-10-2319:23EPSS crossed 10 %FIRST EPSS

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2016-5771?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2016-5771?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

PHP

Branch	Affected	Fixed in	Source
7.0	≥ 7.0.0, < 7.0.8	7.0.8	NVD
5.6	≥ 5.6.0, < 5.6.23	5.6.23	NVD
5.5	< 5.5.37	5.5.37	NVD

Debian debian linux

Branch	Affected	Fixed in	Source
8.0	= 8.0	no fix published	NVD

Opensuse

Branch	Affected	Fixed in	Source
13.2	= 13.2	no fix published	NVD

1 more product in the sources.

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Update PHP to 7.0.8 · 5.6.23 · 5.5.37

Advisories and patches

github.comPatch
php.netPatch · Release Notes · Vendor Advisory
www.openwall.comPatch
bugs.php.netVendor Advisory

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

NVDCVSS 3.19.8read 2026-10-23
NVDCVSS 2.07.5read 2026-10-23
NVDweakness (CWE)CWE-416read 2026-10-23
FIRST EPSSEPSS score15.5 %read 2026-10-23

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published: 2016-08-07
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2016-5771?

Is CVE-2016-5771 actively exploited?

Active exploitation of CVE-2016-5771 has not been confirmed. Its EPSS score was 15.5% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2016-5771?

CVE-2016-5771 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

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