Matrix Rust SDK: Sender-binding gaps in to-device and room-key attribution
Key facts
- Attack vector
- Network
- Privileges required
- High
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- None · High · None
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub. Impact type from CWE-290.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| matrix-org | matrix-rust-sdk | 0.12.0 to before 0.16.1 | 0.16.1 | Patch available | CNA |
| — | matrix-sdk-crypto (crates.io) | 0.12.0 to before 0.16.1 | 0.16.1 | Patch available | GHSA-wfq4-36m3-9g42 |
- matrix-rust-sdk Vendormatrix-org Affected 0.12.0 to before 0.16.1 Fixed in 0.16.1 Patch available CNA
- matrix-sdk-crypto (crates.io) Vendor— Affected 0.12.0 to before 0.16.1 Fixed in 0.16.1 Patch available GHSA-wfq4-36m3-9g42
Remediation
- Fix · CNA matrix-rust-sdk (matrix-org) Fixed in 0.16.1
- Fix · GHSA-wfq4-36m3-9g42 matrix-sdk-crypto (crates.io) Fixed in 0.16.1 Advisory →
Vendor assessments
Timeline
- 2026-10-02 Threatist record created from CVE-2026-45056
- 2026-10-03 Alias added: GHSA-wfq4-36m3-9g42
References
Other 5
- https://github.com/matrix-org/matrix-rust-sdk/security/advisories/GHSA-wfq4-36m3-9g42
- https://github.com/matrix-org/matrix-rust-sdk/pull/6553
- https://github.com/matrix-org/matrix-rust-sdk/releases/tag/matrix-sdk-0.16.1
- https://rustsec.org/advisories/RUSTSEC-2026-0159.html
- https://github.com/matrix-org/matrix-rust-sdk
More matrix-org vulnerabilities
- TI-2023-20035 Sydent does not verify email server certificates CVSS 3.1CRITICAL 9.3
- TI-2026-45046 Dendrite 0.13.8 SSRF via Unauthenticated Legacy Media Download Endpoint CVSS 4.0MEDIUM 6.9
- TI-2026-45045 Dendrite 0.13.8 Improper Authorization via POST account/3pid/delete Endpoint CVSS 4.0HIGH 7.1
- TI-2026-45047 Dendrite 0.13.8 syncapi /context Endpoint Post-Leave State Exposure CVSS 4.0MEDIUM 5.3
- TI-2023-15617 Synapse Outgoing federation to specific hosts can be disabled by sending malicious invites CVSS 3.1MEDIUM 5.0
- TI-2023-20039 matrix-appservice-irc IRC command injection via admin commands containing newlines CVSS 3.1CRITICAL 9.8
Sources
- CVE-2026-45056 · CVE Program
- CVE-2026-45056 · NVD
- FIRST EPSS
- GHSA-wfq4-36m3-9g42 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-45056 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences