CVE-2026-91765: cleanup_xml_node() in the SOAP XML parser recurses once per XML nesting level with no depth limit

This week

HIGH 7.5REMOTEUPGRADE

CVE-2026-91765 is a high-severity flaw (CVSS 7.5) affecting php. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

cleanup_xml_node() in the SOAP XML parser recurses once per XML nesting level with no depth limit. An unauthenticated attacker can post a SOAP request containing tens of thousands of nested elements to any SoapServer endpoint, exhaust the stack and crash the process. The same unbounded recursion exists in the SOAP value decoder and in the WSDL node search helper.

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 57%)
CISA exploited list	No
Weakness	CWE-674
Published	2026-09-25
Last modified	2026-10-23

Publisher (CNA): PHP Group · Vendor: php

Am I affected?

Timeline

2026-09-25 21:17 UTCPublished CVE record published
2026-10-23 13:49 UTCUpdated Record last modified

php php UPGRADE

Affected: >= 8.2.0 and < 8.2.34 · >= 8.3.0 and < 8.3.35 · >= 8.4.0 and < 8.4.26 · >= 8.5.0 and < 8.5.11

Fixed in: 8.2.34, 8.3.35, 8.4.26, 8.5.11

Safe to downgrade to: a release before 8.2.0

1. Check installed version

apt-cache policy php || rpm -q php || php --version

2. UPGRADE to 8.2.34 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade php

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade php

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 8.2.0 (Debian / Ubuntu)

apt-cache madison php sudo apt install php=<VERSION_BEFORE_8.2.0> sudo apt-mark hold php

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list php sudo dnf downgrade php-<VERSION_BEFORE_8.2.0> sudo dnf versionlock add php

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Exact fixes by distribution

Fedora 46 · rubygem-eventmachine · FIXED · 1.2.7-37.fc46 · FEDORA-2026-7194c202a2 · source

sudo dnf upgrade --advisory=FEDORA-2026-7194c202a2

Debian 12 · php8.2 · FIXED · 8.2.34-1~deb12u1

sudo apt update && sudo apt install --only-upgrade php8.2 dpkg --compare-versions "$(dpkg-query -W -f='${Version}' php8.2)" ge "8.2.34-1~deb12u1" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · php8.4 · FIXED · 8.4.26-1~deb13u1

sudo apt update && sudo apt install --only-upgrade php8.4 dpkg --compare-versions "$(dpkg-query -W -f='${Version}' php8.4)" ge "8.4.26-1~deb13u1" && echo PATCHED || echo STILL-VULNERABLE

RHEL 10 · php · FIXED · php-8.3.36-1.el10_2

sudo dnf upgrade --advisory=RHSA-2026:87070 rpm -q php

RHEL 10 · php8.4 · FIXED · php8.4-8.4.27-1.el10_2

sudo dnf upgrade --advisory=RHSA-2026:87071 rpm -q php8.4

RHEL 9 · php · FIXED · php-8.0.30-8.el9_8.1

sudo dnf upgrade --advisory=RHSA-2026:87151 rpm -q php

RHEL 6 · php · NO FIX YET

RHEL 7 · php · NO FIX YET

Alpine 3.22 · php82 · FIXED · php82-8.2.35-r0

apk add --upgrade php82 apk info -v php82

Alpine 3.22 · php83 · FIXED · php83-8.3.36-r0

apk add --upgrade php83 apk info -v php83

Alpine 3.22 · php84 · FIXED · php84-8.4.27-r0

apk add --upgrade php84 apk info -v php84

Alpine 3.23 · php83 · FIXED · php83-8.3.36-r0

apk add --upgrade php83 apk info -v php83

Amazon Linux 2023 · see advisory · FIXED · ALAS2023-2026-3164 · source

sudo dnf update --advisory=ALAS2023-2026-3164

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Write-up: github.com/php/php-src/security/advisories/GHSA-rgrp-mwpx-f6rm

Advisories and coverage

Official advisories

Amazon Linux 2023 ALAS: ALAS2023-2026-3161 (important): php8.2 2026-10-12
Amazon Linux 2023 ALAS: ALAS2023-2026-3162 (important): php8.3 2026-10-12
Amazon Linux 2023 ALAS: ALAS2023-2026-3163 (important): php8.4 2026-10-12
Amazon Linux 2023 ALAS: ALAS2023-2026-3164 (important): php8.5 2026-10-12
Amazon Linux 2 ALAS: ALAS2PHP8.2-2026-014 (important): php 2026-10-12

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Related CVEs

CVE-2026-17544 CRITICAL 9.8 UPGRADE Attacker-provided inputs to bccomp() could lead to an out-of-bounds write with stack and heap corruption in PH
CVE-2026-17543 CRITICAL 9.8 UPGRADE Improper escaping of backslashes in attacker-provided parameters would allow for trivial SQL injection in PHP
CVE-2026-7260 MEDIUM 5.5 UPGRADE Circular symbolic links in phar archives could lead to unbounded recursion, exhausting the C stack and crashin
CVE-2026-109618 CRITICAL 9.8 UPGRADE MITIGATE PHP uses longjmp() for out-of-memory (OOM) errors to exit the current context and abort handling of the reques
CVE-2026-109619 HIGH 8.1 UPGRADE MITIGATE PHP has various global state that temporarily points into request memory

References

← Back to latest CVEs