What is CVE-2026-45057?

CVE-2026-45057 is matrix-sdk-ui: Incomplete edit validation. The supplied enrichment data classifies it as Unclassified mapped to CWE-345 CWE-345.

Which versions are affected?

Affected product and version evidence is listed in the product table above. Current public advisories should be checked for exact version scope before patch targeting is finalized.

Is there active exploitation?

Active exploitation is not confirmed from current sources for CVE-2026-45057. If exploitation is not confirmed from current sources, teams should document that status and continue monitoring KEV, vendor, and telemetry updates.

No. CVE-2026-45057 is not listed in CISA KEV in the supplied enrichment data. KEV status should be monitored because it can change after initial disclosure or after exploitation becomes publicly confirmed.

Is there a public exploit?

A public PoC is not confirmed from current sources for CVE-2026-45057. Public exploit or PoC availability should raise triage priority, especially for exposed or business-critical systems.

How can defenders detect it?

Start with web/proxy/WAF logs, application logs, network IDS/IPS where available. Look for vulnerability-class behavior, product errors, suspicious authentication events, exploit probes, and abnormal process activity based only on evidence that applies to the affected product.

How should teams prioritize it?

Prioritize CVE-2026-45057 using CVSS 4.9, EPSS 0%, KEV status, public PoC status, and asset exposure. Internet-facing, privileged, or business-critical deployments should be handled first.

Are workarounds available?

Workarounds are not confirmed from current sources. Fixed-version evidence is listed in the mitigation section above.

Which threat actors are linked publicly?

No public threat actor linkage is confirmed from current sources. Do not attribute exploitation to a threat actor unless the source evidence explicitly supports that linkage.

What should be done in the next 24 hours?

Identify exposed assets running affected vendor/product/version combinations. Prioritize based on EPSS, PoC availability, and external exposure. Search available logs for exploit probes, errors, authentication anomalies, or suspicious child processes matching the vulnerability class. Open remediation tickets with affected assets, owners, evidence status, and detection coverage so decisions are traceable.

medium

CVE-2026-45057

CVE-2026-45057 — matrix-sdk-ui: Incomplete edit validation

matrix-sdk-ui provides GUI-centric utilities on top of matrix-rust-sdk. The message edit validation logic in the `matrix-sdk-ui` crate prior to 0.17.0 is missing a check: when replacing an encrypted event, the replacement event itself is not required to be encrypted. This enables a malicious homeserver administrators (or actors with equivalent power) to impersonate or spoof messages as if they were sent by a victim user. `matrix-sdk-ui` 0.17.0 fixes the message edit validation logic to align with the algorithm for replacement events[^1] described in the Matrix specification. No known workarounds are available.

Published Sep 11, 2026Updated Sep 11, 2026Sources: NVD, matrix-org (CNA), GitHub, GitHub Security Advisory, SOCRadar CTI

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the scoring sources call it.

Exploitation

Unreported

no source claims exploitation

EPSS

ahead of 5% of scored CVEs

Affects

matrix-org

2 products listed

CVSS base

4.9

medium

Remediation

The vendor's own words where we have them.

Upgrade matrix-sdk-ui to 0.16.1 or later (rust advisory GHSA-h97m-27fx-42rx).

First 24 hours

Ordered from the record's own fields — exposure first, because you cannot patch what you have not found.

Identify exposed assets running affected vendor/product/version combinations.
Prioritize based on EPSS, PoC availability, and external exposure.
Search available logs for exploit probes, errors, authentication anomalies, or suspicious child processes matching the vulnerability class.

Affected scope

Vendor, product and version as the advisories word them.

Vendor	Product	Versions	Status
matrix-org	matrix-sdk-ui	< 0.16.1	Vulnerable
rust	matrix-sdk-ui	< 0.16.1	Vulnerable

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Availability

None

Confidentiality

None

Integrity

High

Scope

Unchanged

Attack Complexity

Low

Attack Vector

Network

Privileges Req

High

User Interaction

None

Every base score collected

Sources score independently and disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Source
4.9	CVSS 3.1	medium	1.2	3.6	GitHub (CNA), matrix-org (CNA), GHSA

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N

What this weakness leads to

MITRE's own consequences and mitigations for the weakness class — the authority's wording, not guidance derived from the CVSS vector.

MITRE

CWE-345 · Insufficient Verification of Data Authenticity

Varies by Context
Unexpected State::

Weakness & attack patterns

CWE-345

Attack patterns reported against this CVE. The ATT&CK techniques below are inferred from its weakness class.

CAPEC-387 · Navigation Remapping To Propagate Malicious ContentCAPEC-218 · Spoofing of UDDI/ebXML MessagesCAPEC-148 · Content SpoofingCAPEC-142 · DNS Cache PoisoningCAPEC-388 · Application API Button HijackingCAPEC-386 · Application API Navigation RemappingCAPEC-384 · Application API Message Manipulation via Man-in-the-MiddleCAPEC-141 · Cache PoisoningCAPEC-111 · JSON Hijacking (aka JavaScript Hijacking)CAPEC-385 · Transaction or Event Tampering via Application API Manipulation

T1557.002Adversary-in-the-Middle: ARP Cache Poisoning
T1584.002Compromise Infrastructure: DNS Server
T1491Defacement

Detection

Read off the CVSS vector and the weakness class. Starting points, not rules we have tested.

Prioritize edge telemetry for network-reachable matrix-sdk-ui.

web/proxy/WAF logsapplication logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first — with the readings a source repeats on a schedule counted underneath rather than listed.

2026
Added · CVSS 3.1 4.9 (AV:N)
Sep 11, 2026 · NVD
Initial · CVE published
Sep 11, 2026 · NVD
CVE published by MITRE.
Sep 11, 2026 · SOCRadar CTI
Added · GHSA-h97m-27fx-42rx published (medium)
Jun 4, 2026 · GitHub Security Advisory

References

5 on the record

github.com/matrix-org/matrix-rust-sdk/pull/6454
Exploit, Third Party Advisory, Mitre
github.com/matrix-org/matrix-rust-sdk/releases/tag/matrix-sdk-0.16.1
Exploit, Third Party Advisory, Mitre
github.com/matrix-org/matrix-rust-sdk/security/advisories/GHSA-h97m-27fx-42rx
Exploit, Third Party Advisory, Mitre
rustsec.org/advisories/RUSTSEC-2026-0158.html
Vendor Advisory, Mitre
github.com/advisories/GHSA-h97m-27fx-42rx
Exploit, Third Party Advisory

Elsewhere on this site

matrix-orgevery CVE for this vendor
rustevery CVE for this vendor
Unclassifiedsame class
CWE-345other pages naming this weakness

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record1

What should defenders know first?

CVE-2026-45057 is matrix-sdk-ui: Incomplete edit validation, a medium vulnerability affecting matrix-sdk-ui from matrix-org, rust. The current evidence does not list it in CISA KEV, and the exploit status is: Active exploitation is not confirmed from current sources for CVE-2026-45057. Public exploit evidence is: A public PoC is not confirmed from current sources for CVE-2026-45057. The affected-version evidence is listed in the key facts and affected products tables. Defenders should first verify whether exposed or business-critical assets run those versions, then apply vendor patches or mitigations, restrict reachable attack surface, and preserve logs for detection review. CVSS 4.9 describes technical severity, while EPSS 0% helps estimate near-term exploit likelihood; neither replaces asset context. Unknown fields should remain explicit in tickets, and threat actor, IOC, victimology, or payload claims should not be added unless a cited source supports them. Monitor CISA KEV, vendor advisories, NVD changes, public PoC repositories, and internal telemetry for update triggers.