CVE-2025-66622: matrix-sdk-base is the base component to build a Matrix client library

Q: How do I fix CVE-2025-66622?

matrix-rust-sdk: upgrade to 0.16.0. Exact commands for each OS are on this page.

Q: Is CVE-2025-66622 being exploited?

CVE-2025-66622 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2025-66622 affect?

CVE-2025-66622 affects matrix-rust-sdk. Severity is high (CVSS 7.5). matrix-sdk-base is the base component to build a Matrix client library. Versions 0.14.1 and prior are unable to handle responses that include custom m.room.join_rules values due to a serialization bug. This can be exploited to cause a denia

Q: How urgent is CVE-2025-66622?

Priority 40/100. High severity; Remotely exploitable, no login, no user action

This month

HIGH 7.5REMOTEUPGRADE

CVE-2025-66622 is a high-severity flaw (CVSS 7.5) affecting matrix-rust-sdk. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

matrix-sdk-base is the base component to build a Matrix client library. Versions 0.14.1 and prior are unable to handle responses that include custom m.room.join_rules values due to a serialization bug. This can be exploited to cause a denial-of-service condition, if a user is invited to a room with non-standard join rules, the crate's sync process will stall, preventing further processing for all rooms. This is fixed in version 0.16.0.

Why this priority

High severity
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	0.4% (top 64%)
CISA exploited list	No
Weakness	CWE-755
Published	2025-12-09
Last modified	2026-10-07

Publisher (CNA): GitHub, Inc. · Vendor: matrix

Last updated 2026-10-07 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2025-12-09 16:18 UTCPublished CVE record published
2026-10-07 20:10 UTCUpdated Record last modified

matrix matrix-rust-sdk UPGRADE

Affected: < 0.16.0

Fixed in: 0.16.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy matrix-rust-sdk || rpm -q matrix-rust-sdk || matrix-rust-sdk --version

2. UPGRADE to 0.16.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade matrix-rust-sdk

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade matrix-rust-sdk

Note

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

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-2025-66622?

matrix-rust-sdk: upgrade to 0.16.0. Exact commands for each OS are on this page.

Is CVE-2025-66622 being exploited?

CVE-2025-66622 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-2025-66622 affect?

CVE-2025-66622 affects matrix-rust-sdk. Severity is high (CVSS 7.5). matrix-sdk-base is the base component to build a Matrix client library. Versions 0.14.1 and prior are unable to handle responses that include custom m.room.join_rules values due to a serialization bug. This can be exploited to cause a denia

How urgent is CVE-2025-66622?

Priority 40/100. High severity; Remotely exploitable, no login, no user action

References

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