6.9

CVE-2026-45056: matrix-org matrix-rust-sdk Authentication Bypass by Spoofing

CVSS: 6.9v4.0MediumDeferred
AliasesGHSA-wfq4-36m3-9g42RUSTSEC-2026-0159
Published 11-09-2026Last modified 14-09-2026
Open JSON

Vulnerability summary

CVE-2026-45056 is a medium (CVSS 6.9) Authentication Bypass by Spoofing vulnerability in matrix-org matrix-rust-sdk. EPSS estimates a 0.31% chance of exploitation in the next 30 days, higher than 22.1% of scored vulnerabilities.

Overall risk
28/100
0100
Medium · default modelHow is this calculated?
CVSS score
6.9/10
010
Medium · v4.0 (CVE.org)
EPSS score
0.31%
0%100%
Low · +0.07 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 11-09-2026
    PublishedVulnerability first disclosed.
  2. 14-09-2026
    Last modifiedVulnerability information updated.

Description

matrix-sdk-crypto is a no-network-IO implementation of a state machine that handles end-to-end encryption for Matrix clients. Starting in version 0.12.0 and prior to version 0.17.0, the matrix-sdk-crypto crate was missing a check for the user ID when decrypting an Olm-encrypted event containing the `sender_device_keys` property. This could be exploited to forge an encrypted to-device event, but only if the attacker colludes with the homeserver operator. This issue is fixed in matrix-sdk-crypto 0.17.0. There are no known workarounds for the issue.

CVSS metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.31%

Chance of exploitation in the next 30 days

Percentile

22%

Versus all other CVEs

30-day change

+0.07 pp

From 0.23% on 19-09-2026

19-09-202619-10-2026
EPSS score
0.31%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Crates.Io1 product
  • matrix-sdk-crypto≥ 0.12.0, < 0.16.1
Matrix-org1 product

2 vendors · 2 products

References

6 links