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Fencer Intel
critical 9.8

CVE-2016-5771 in the critical feed json

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…

published 2016-08-07 10 y ago modified 2026-06-17 4 mo ago also EUVD-2016-6706

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
15.5%
EPSS 15.5% chance of exploitation in 30 days, percentile 96%
public exploits
0
none known

Summary

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.

Patch / fix

  • php php 5.5.37, 5.6.23, 7.0.8
  • php5 Ubuntu 14.04 LTS 5.5.9+dfsg-1ubuntu4.19

ubuntu advisories UBUNTU-CVE-2016-5771

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • rh-php56 RHEL 2 SOFTWARE_COLLECTIONS 2.3-1.el6
  • rh-php56 RHEL 2 SOFTWARE_COLLECTIONS 2.3-1.el7
  • rh-php56-php RHEL 2 SOFTWARE_COLLECTIONS 5.6.25-1.el6
  • rh-php56-php RHEL 2 SOFTWARE_COLLECTIONS 5.6.25-1.el7
  • rh-php56-php-gd RHEL 2 SOFTWARE_COLLECTIONS 5.6.25-1.el6
  • rh-php56-php-gd RHEL 2 SOFTWARE_COLLECTIONS 5.6.25-1.el7
  • rh-php56-php-cli RHEL 2 SOFTWARE_COLLECTIONS 5.6.25-1.el6
  • rh-php56-php-cli RHEL 2 SOFTWARE_COLLECTIONS 5.6.25-1.el7

red hat advisories RHSA-2016:2750

  • php53 SLES for SAP 11 SP4, SLES 11 SP4, SLES 11 SP3-TERADATA +3 more 5.3.17-112.20.1
  • php5 SLE Software Development Kit 12 SP1, SLE Module for Web and Scripting 12 5.5.14-68.1

suse advisories SUSE-SU-2018:0806-1SUSE-SU-2016:1842-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2016-5771 updated cvss 5.6

php: Use After Free Vulnerability in PHP's GC algorithm and unserialize

  • Red Hat Enterprise Linux 5 php, php53 Red Hat Enterprise Linux 6 php, php-gd, php-cli, php-dba, php-fpm, php-pdo, +20 more Red Hat Enterprise Linux 7 php, php-gd, php-cli, php-dba, php-fpm, php-pdo, +18 more Red Hat Software Collections php54-php, php55-php, php54-php-gd, php55-php-gd, php54-php-cli, php54-php-dba, +44 more
    affected: no fix planned “Will not fix”
  • Red Hat Software Collections for Red Hat Enterprise Linux Server (v. 6) rh-php56 2.3-1.el6, rh-php56-php 5.6.25-1.el6, rh-php56-runtime 2.3-1.el6, rh-php56-scldevel 2.3-1.el6, rh-php56-php-gd 5.6.25-1.el6, rh-php56-php-cli 5.6.25-1.el6, +26 more Red Hat Software Collections for Red Hat Enterprise Linux Server (v. 7) rh-php56 2.3-1.el7, rh-php56-php 5.6.25-1.el7, rh-php56-runtime 2.3-1.el7, rh-php56-scldevel 2.3-1.el7, rh-php56-php-gd 5.6.25-1.el7, rh-php56-php-cli 5.6.25-1.el7, +24 more Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 6.7) rh-php56 2.3-1.el6, rh-php56-php 5.6.25-1.el6, rh-php56-runtime 2.3-1.el6, rh-php56-scldevel 2.3-1.el6, rh-php56-php-gd 5.6.25-1.el6, rh-php56-php-cli 5.6.25-1.el6, +26 more Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 7.2) rh-php56 2.3-1.el7, rh-php56-php 5.6.25-1.el7, rh-php56-runtime 2.3-1.el7, rh-php56-scldevel 2.3-1.el7, rh-php56-php-gd 5.6.25-1.el7, rh-php56-php-cli 5.6.25-1.el7, +24 more Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 7.3) rh-php56 2.3-1.el7, rh-php56-php 5.6.25-1.el7, rh-php56-runtime 2.3-1.el7, rh-php56-scldevel 2.3-1.el7, rh-php56-php-gd 5.6.25-1.el7, rh-php56-php-cli 5.6.25-1.el7, +24 more Red Hat Software Collections for Red Hat Enterprise Linux Workstation (v. 6) rh-php56 2.3-1.el6, rh-php56-php 5.6.25-1.el6, rh-php56-runtime 2.3-1.el6, rh-php56-scldevel 2.3-1.el6, rh-php56-php-gd 5.6.25-1.el6, rh-php56-php-cli 5.6.25-1.el6, +26 more
    +1 more products
    Red Hat Software Collections for Red Hat Enterprise Linux Workstation (v. 7) rh-php56 2.3-1.el7, rh-php56-php 5.6.25-1.el7, rh-php56-runtime 2.3-1.el7, rh-php56-scldevel 2.3-1.el7, rh-php56-php-gd 5.6.25-1.el7, rh-php56-php-cli 5.6.25-1.el7, +24 more
    fixed: vendor fix RHSA-2016:2750

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

15.48% chance of exploitation in the next 30 days, higher than 96% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • bugs.php.net https://bugs.php.net/bug.php?id=72433 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P

Classification

Weakness
Technology feeds

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.