CVE-2026-45056Published

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

Collected exploitation and prediction evidence

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

cve-program · CVE-2026-45056

Published

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.

Source published: 11 Sep 2026 21:13:56 UTC
Source modified: 14 Sep 2026 18:17:31 UTC
Observed here: 23 Oct 2026 15:48:27 UTC
Source terms: CVE Program Terms of Use

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CVSS 4.0 · 6.9 CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

euvd · EUVD-2026-76763

Published

EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON.

Original publisher date fields

datePublished: Sep 11, 2026, 9:13:56 PM

dateUpdated: Sep 14, 2026, 6:17:31 PM

Source published: Sep 11, 2026, 9:13:56 PM (timezone not stated)
Source modified: Sep 14, 2026, 6:17:31 PM (timezone not stated)
Observed here: 9 Nov 2026 14:05:26 UTC
Source terms: ENISA EUVD · source terms and attribution apply

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EUVD CVSS 4.0 · 6.9 CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

nvd · CVE-2026-45056

Published

NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON.

Source analysis status: Deferred

Weakness classifications: CWE-290

Original publisher date fields

published: 2026-09-11T22:16:37.263

lastModified: 2026-09-30T19:57:08.043

Source published: 11 Sep 2026 22:16:37 UTC
Source modified: 30 Sep 2026 19:57:08 UTC
Observed here: 25 Oct 2026 10:17:33 UTC
Source terms: NIST NVD usage terms; underlying source attribution retained

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · [email protected] · Secondary · 6.9 CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/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

osv · GHSA-wfq4-36m3-9g42

Published

### 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](mailto:[email protected]).

Source published: 4 Jun 2026 14:47:05 UTC
Source modified: 4 Jun 2026 15:00:08 UTC
Observed here: 24 Oct 2026 13:19:54 UTC
Source terms: GitHub Advisory Database · CC-BY-4.0

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CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

Publisher rating · MODERATE

osv · RUSTSEC-2026-0159

Published

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.

Source published: 3 Jun 2026 12:00:00 UTC
Source modified: 12 Oct 2026 18:00:09 UTC
Observed here: 24 Oct 2026 13:19:54 UTC
Source terms: OSV · upstream source license applies

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · OSV · upstream source license applies. Source text is retained; field grouping and change labels are provided by ChangeIntel.