CVE-2026-91769: PHP's OpenSSL stream peer verification checks the certificate's subjectAltName entries first and, whenever no

Routine

MEDIUM 4.3WATCHLISTUPGRADE

CVE-2026-91769 is a medium-severity flaw (CVSS 4.3) affecting php. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

PHP's OpenSSL stream peer verification checks the certificate's subjectAltName entries first and, whenever no entry matches, falls back to the Common Name. RFC 6125 requires the CN to be ignored once the certificate presents any service identity, so a certificate carrying a non-matching DNS SAN was still accepted when its CN matched the requested peer_name. A certificate trusted by the client for one name can therefore be used to impersonate anot

Why this priority

Public exploit reference
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	4.3 (Medium)
Attack vector	Adjacent network
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.1% (top 97%)
CISA exploited list	No
Weakness	CWE-297
Published	2026-09-25
Last modified	2026-10-23

Publisher (CNA): PHP Group · Vendor: php

Last updated 2026-10-23 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-09-25 21:17 UTCPublished CVE record published
2026-10-23 13:20 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

Ubuntu 20.04 · php7.4 · FIXED · 7.4.3-4ubuntu2.29+esm4

sudo apt update && sudo apt install --only-upgrade php7.4 dpkg --compare-versions "$(dpkg-query -W -f='${Version}' php7.4)" ge "7.4.3-4ubuntu2.29+esm4" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 22.04 · php8.1 · FIXED · 8.1.2-1ubuntu2.27

sudo apt update && sudo apt install --only-upgrade php8.1 dpkg --compare-versions "$(dpkg-query -W -f='${Version}' php8.1)" ge "8.1.2-1ubuntu2.27" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 24.04 · php8.3 · FIXED · 8.3.6-0ubuntu0.24.04.12

sudo apt update && sudo apt install --only-upgrade php8.3 dpkg --compare-versions "$(dpkg-query -W -f='${Version}' php8.3)" ge "8.3.6-0ubuntu0.24.04.12" && echo PATCHED || echo STILL-VULNERABLE

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 · DEFERRED

RHEL 10 · php8.4 · DEFERRED

RHEL 6 · php · DEFERRED

RHEL 7 · php · DEFERRED

RHEL 8 · php:8.2/php · DEFERRED

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

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.

Quick answers

How do I fix CVE-2026-91769?

php: upgrade to 8.2.34, 8.3.35, 8.4.26, 8.5.11. Exact commands for each OS are on this page.

Is CVE-2026-91769 being exploited?

CVE-2026-91769 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-91769 affect?

CVE-2026-91769 affects php. Severity is medium (CVSS 4.3). PHP's OpenSSL stream peer verification checks the certificate's subjectAltName entries first and, whenever no entry matches, falls back to the Common Name. RFC 6125 requires the CN to be ignored once the certificate presents any service ide

How urgent is CVE-2026-91769?

Priority 26/100. Public exploit reference; On your watchlist

Software pages

OpenSSL vulnerabilities · PHP vulnerabilities

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References

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