CVE-2026-45056

MEDIUMCVSS · not yet scored
—
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • No CVSS published and no exploitation signals yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS v2: —Exploit: None knownExposed: 0

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

Matrix Rust SDK: Sender-binding gaps in to-device and room-key attribution

Impact

The matrix-sdk-crypto crate before 0.16.1 is missing a check for the sender's user ID when decrypting an Olm-encrypted to-device message containing the sender_device_keys property.

This could be exploited to spoof the sender of an encrypted to-device message, but only if the attacker colludes with (or is) the homeserver operator.

Patches

This issue is fixed in matrix-sdk-crypto 0.16.1.

Workarounds

There are no known workarounds for the issue.

References

This issue was fixed in https://github.com/matrix-org/matrix-rust-sdk/pull/6553.

For more information

If you have any questions or comments about this advisory, please email us at security at matrix.org.

CVSS v3
—
EchelonGraph score
Not yet assessedNo source has published severity data for this CVE yet — no CVSS score from NVD or a CNA, no GitHub advisory, and it is not in CISA KEV. This is not a rating of zero; we cannot assess it yet.
EG Score
—
EG Risk
—
EPSS PROB
0%
EPSS %ILE
16%
KEV
Not listed

Published

June 4, 2026

Last Modified

June 4, 2026

Vendor Advisories for CVE-2026-45056(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(1 across 1 ecosystem)
crates.io(1)
PackageVulnerable rangeFixed inDependents
matrix-sdk-crypto—0.16.1—

Data Freshness Timeline

(refreshed 0× in last 7d / 1× 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.

  1. 2026-07-31 05:26 UTCEG score recompute
  2. 2026-07-26 22:16 UTCEG score recompute
  3. 2026-07-23 03:16 UTCEG score recompute
  4. 2026-06-14 23:18 UTCEPSS rescore
  5. 2026-06-13 23:00 UTCEPSS rescore
  6. 2026-06-12 23:12 UTCEPSS rescore
  7. 2026-06-04 15:10 UTCEG score recompute

Frequently asked(4)

What is CVE-2026-45056?
CVE-2026-45056 is a medium vulnerability published on June 4, 2026. Matrix Rust SDK: Sender-binding gaps in to-device and room-key attribution Impact The matrix-sdk-crypto crate before 0.16.1 is missing a check for the sender's user ID when decrypting an Olm-encrypted to-device message containing the senderdevicekeys property. This could be exploited to spoof the…
When was CVE-2026-45056 disclosed?
CVE-2026-45056 was first published in the National Vulnerability Database on June 4, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-45056 actively exploited?
CVE-2026-45056 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 83.8% of all scored CVEs.
How do I remediate CVE-2026-45056?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-45056, 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.

Dependency Blast Radius

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