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CVE-2025-66622

24
FAUCET Score

CVE-2025-66622 is a denial-of-service vulnerability affecting matrix-sdk-base versions 0.14.1 and prior. A serialization bug prevents the software from properly handling custom m.room.join_rules values, causing the sync process to stall if a user is invited to a room with non-standard join rules. This vulnerability has a low CVSS score of 1.3, indicating a low attack complexity and impact, as it requires user interaction (UI:P) and only leads to a low availability impact (VA:L). There is currently no known active exploitation, publicly available exploit code, or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 0.16.0CPE matchmatch criteria
cpe:2.3:a:matrix:matrix-rust-sdk:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 4.0

1.3LOW

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
PASSIVE
VS Confidentiality
NONE
VS Integrity
NONE
VS Availability
LOW
SS Confidentiality
NONE
SS Integrity
NONE
SS Availability
NONE
Exploit Maturity
UNREPORTED
CvssVersion
4.0

Exploit Intelligence

EPSS Score
0.36%
Probability of exploitation in next 30 days
EPSS Percentile
28.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0036 is in the 9th percentile among its peer group of 51,506 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (1)

rustpatch availablevia ghsa
Product: matrix-sdk-baseFixed in: 0.16.0

Vendor Advisories (1)

rustGHSA-jj6p-3m75-g2p3low

matrix-sdk-base denial of service via custom m.room.join_rules event values

Dec 8, 2025

References

github.com / matrix-org/matrix-rust-sdk/commit/4ea0418abefab2aa93f8851a4d39c723e703e6b0
Patch
github.com / matrix-org/matrix-rust-sdk/pull/5924
Issue TrackingPatch
github.com / matrix-org/matrix-rust-sdk/security/advisories/GHSA-jj6p-3m75-g2p3
PatchVendor Advisory
rustsec.org / advisories/RUSTSEC-2025-0135.html
Third Party Advisory