CVE-2025-66622

HIGHNVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 0.4%, top 67% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.5Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
7.5
EG Score
7.5(medium)
EG Risk
49(Track)
EG Risk 49/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity75% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
35%
KEV
Not listed

Published

December 9, 2025

Last Modified

June 17, 2026

Advisory Details (4)

Auto-updated Aug 8, 2026
Patch available. Sources: github_pr, github, github_commit.
generic

RUSTSEC-2025-0135: matrix-sdk-base: matrix-sdk-base: Denial of service due to custom `m.room.join_rules` events › RustSec Advisory Database

https://rustsec.org/advisories/RUSTSEC-2025-0135.html
github Patch Available

Denial of service due to custom `m.room.join_rules` events · Advisory · matrix-org/matrix-rust-sdk · GitHub

https://github.com/matrix-org/matrix-rust-sdk/security/advisories/GHSA-jj6p-3m75-g2p3
github_pr Patch Available

fix: Don't attempt to serialize custom join rules

Patch available: matrix-org/matrix-rust-sdk matrix-sdk-0.16.0 (PR #5924 merged 2025-12-03)

https://github.com/matrix-org/matrix-rust-sdk/pull/5924
github_commit Patch Available

commit 4ea0418abefa (matrix-org/matrix-rust-sdk)

Patch available: matrix-org/matrix-rust-sdk matrix-sdk-0.16.0 (contains commit 4ea0418abefa)

https://github.com/matrix-org/matrix-rust-sdk/commit/4ea0418abefab2aa93f8851a4d39c723e703e6b0

Affected Packages

(1 across 1 ecosystem)
crates.io(1)
PackageVulnerable rangeFixed inDependents
matrix-sdk-base—0.16.0—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 5× in last 7d / 27× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 149 total refreshes for this CVE.

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Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2025-66622?
CVE-2025-66622 is a high vulnerability published on December 9, 2025. 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…
When was CVE-2025-66622 disclosed?
CVE-2025-66622 was first published in the National Vulnerability Database on December 9, 2025, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2025-66622 actively exploited?
CVE-2025-66622 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 64.7% of all scored CVEs.
What is the CVSS score of CVE-2025-66622?
CVE-2025-66622 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2025-66622?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2025-66622, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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