CVE-2026-81525: The MongoDB client library for PHP does not sufficiently sanitize special elements in application-supplied nam

Routine

HIGH 8.1UPGRADEUPGRADE

CVE-2026-81525 is a high-severity flaw (CVSS 8.1) affecting php driver, php library. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The MongoDB client library for PHP does not sufficiently sanitize special elements in application-supplied namespace identifiers before using them to construct the target namespace for database operations. An application that incorporates untrusted text into these identifiers may have operations silently directed at a different storage location than the one the application intended.

Why this priority

High severity

A fixed release or distro patch exists.

Risk facts

CVSS score	8.1 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.5% (top 58%)
CISA exploited list	No
Weakness	CWE-943
Published	2026-08-27
Last modified	2026-09-29

Publisher (CNA): MongoDB, Inc. · Vendor: mongodb

Last updated 2026-09-29 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-08-27 20:18 UTCPublished CVE record published
2026-09-29 19:17 UTCUpdated Record last modified

mongodb php driver UPGRADE

Affected: < 1.21.6 · >= 2.0.0 and < 2.4.1

Fixed in: 1.21.6, 2.4.1

Safe to downgrade to: a release before 2.0.0

1. Check installed version

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

2. UPGRADE to 1.21.6 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade php-driver

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 2.0.0 (Debian / Ubuntu)

apt-cache madison php-driver sudo apt install php-driver=<VERSION_BEFORE_2.0.0> sudo apt-mark hold php-driver

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

dnf --showduplicates list php-driver sudo dnf downgrade php-driver-<VERSION_BEFORE_2.0.0> sudo dnf versionlock add php-driver

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.

mongodb php library UPGRADE

Affected: < 1.21.4 · >= 2.0.0 and < 2.4.1

Fixed in: 1.21.4, 2.4.1

Safe to downgrade to: a release before 2.0.0

1. Check installed version

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

2. UPGRADE to 1.21.4 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade php-library

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 2.0.0 (Debian / Ubuntu)

apt-cache madison php-library sudo apt install php-library=<VERSION_BEFORE_2.0.0> sudo apt-mark hold php-library

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

dnf --showduplicates list php-library sudo dnf downgrade php-library-<VERSION_BEFORE_2.0.0> sudo dnf versionlock add php-library

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.

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-2026-81525?

php driver: upgrade to 1.21.6, 2.4.1; php library: upgrade to 1.21.4, 2.4.1. Exact commands for each OS are on this page.

Is CVE-2026-81525 being exploited?

CVE-2026-81525 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-2026-81525 affect?

CVE-2026-81525 affects php driver, php library. Severity is high (CVSS 8.1). The MongoDB client library for PHP does not sufficiently sanitize special elements in application-supplied namespace identifiers before using them to construct the target namespace for database operations. An application that incorporates u

How urgent is CVE-2026-81525?

Priority 39/100. High severity

Software pages

PHP vulnerabilities · MongoDB vulnerabilities

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References

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