CVE-2025-48937 is a medium-severity (CVSS 4.9) CWE-290 vulnerability in matrix-sdk-crypto. A fix is available for matrix-sdk-crypto — see the affected versions and patch details below.
matrix-sdk-crypto vulnerable to sender of encrypted events being spoofed by homeserver administrator
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2025-48937.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2025-48937 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,333 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
matrix-sdk-cryptoReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.
Description
Summary
matrix-sdk-crypto since version 0.8.0 up to 0.11.0 does not correctly validate the sender of an encrypted event. Accordingly, a malicious homeserver operator can modify events served to clients, making those events appear to the recipient as if they were sent by another user.
Although the CVSS score is 4.9 (AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N), we consider this a High Severity security issue.
Details
The Matrix specification requires that clients ensure that "the event’s sender, room_id, and the recorded session_id match a trusted session". The vulnerable matrix-sdk-crypto versions check that the room_id matches that of the session denoted by session_id, but do not check the sender.
Patches
The issue is resolved by 13c1d20, included in versions 0.11.1 and 0.12.0 of matrix-sdk-crypto.
Workarounds
Since a successful attack requires administrator access to the homeserver, users who trust the administrators of their local homeserver are not affected.
References
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | matrix-sdk-crypto | ≥ 0.8.0&&< 0.11.1 | 0.11.1cargo update -p matrix-sdk-crypto --precise 0.11.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for matrix-sdk-crypto, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update matrix-sdk-crypto to 0.11.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-48937 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2025-48937 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2025-48937. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2025-48937 in your dependencies?
O3 Security finds CVE-2025-48937 across crates.io dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.