How severe is CVE-2025-66622?

CVE-2025-66622 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2025-66622 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (28th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-66622?

CVE-2025-66622 affects Matrix Matrix-rust-sdk. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2025-66622?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2025-66622 have an EU (EUVD) identifier?

Yes. CVE-2025-66622 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-201827.

When was CVE-2025-66622 published?

CVE-2025-66622 was published on 2025-12-09 and last updated on 2026-06-17.

CVE-2025-66622

CVE-2025-66622 is a high-severity vulnerability in Matrix Matrix-rust-sdk with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-755.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v4: 1.3
EPSS exploit prediction: 0% (28th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-201827
Weakness: CWE-755
Affected product: Matrix Matrix-rust-sdk
Published: 2025-12-09
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2025-66622?: 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.
How severe is CVE-2025-66622?: CVE-2025-66622 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2025-66622 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (28th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-66622?: CVE-2025-66622 affects Matrix Matrix-rust-sdk. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2025-66622?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2025-66622 have an EU (EUVD) identifier?: Yes. CVE-2025-66622 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-201827.
When was CVE-2025-66622 published?: CVE-2025-66622 was published on 2025-12-09 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:matrix:matrix-rust-sdk:*:*:*:*:*:*:*:*

More vulnerabilities in Matrix Matrix-rust-sdk

CVE-2022-39252 — High (CVSS 8.6): matrix-rust-sdk is an implementation of a Matrix client-server library in Rust, and matrix-sdk-crypto is the Matrix…

All CVEs affecting Matrix Matrix-rust-sdk →

Other CWE-755 (Improper Handling of Exceptional Conditions) vulnerabilities

CVE-2025-34193 — Critical (CVSS 9.8): Vasion Print (formerly PrinterLogic) Virtual Appliance Host versions prior to 25.1.102 and Application versions prior…
CVE-2025-10156 — Critical (CVSS 9.8): An Improper Handling of Exceptional Conditions vulnerability in the ZIP archive scanning component of mmaitre314…
CVE-2021-42142 — Critical (CVSS 9.8): An issue was discovered in Contiki-NG tinyDTLS through master branch 53a0d97. DTLS servers mishandle the early use of a…
CVE-2021-42141 — Critical (CVSS 9.8): An issue was discovered in Contiki-NG tinyDTLS through 2018-08-30. One incorrect handshake could complete with…
CVE-2023-38406 — Critical (CVSS 9.8): bgpd/bgp_flowspec.c in FRRouting (FRR) before 8.4.3 mishandles an nlri length of zero, aka a "flowspec overflow."
CVE-2022-23121 — Critical (CVSS 9.8): This vulnerability allows remote attackers to execute arbitrary code on affected installations of Netatalk.…

Browse all CWE-755 (Improper Handling of Exceptional Conditions) vulnerabilities →