CVE-2025-48937 – This vulnerability in matrix-rust-sdk allows ma... (How to Fix)

📋 TL;DR

This vulnerability in matrix-rust-sdk allows malicious homeserver operators to modify encrypted events, making them appear to be sent by different users. It affects all clients using vulnerable versions of the library, potentially enabling impersonation attacks in Matrix communications.

💻 Affected Systems

Products:

matrix-rust-sdk
matrix-sdk-crypto

Versions: matrix-sdk-crypto versions 0.8.0 through 0.11.0

Operating Systems: All platforms using affected library

Default Config Vulnerable: ⚠️ Yes

Notes: Affects any application using the vulnerable matrix-sdk-crypto library for Matrix client-server communication.

⚠️ Manual Verification Required

This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.

Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).

🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.

Recommended Actions:

Review the CVE details at NVD
Check vendor security advisories for your specific version
Test if the vulnerability is exploitable in your environment
Consider updating to the latest version as a precaution

⚠️ Risk & Real-World Impact

🔴

Worst Case

Malicious homeserver operators could impersonate any user in encrypted conversations, leading to misinformation, social engineering attacks, or manipulation of group decisions.

🟠

Likely Case

Malicious server administrators could selectively modify messages to appear from other users, potentially causing confusion or minor trust issues in affected conversations.

🟢

If Mitigated

With proper server trust controls and client verification, impact is limited to untrusted servers where users already assume risk.

🌐 Internet-Facing: MEDIUM

🏢 Internal Only: MEDIUM

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Exploitation requires control of the homeserver, limiting attack surface to malicious server operators rather than arbitrary attackers.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: matrix-sdk-crypto 0.11.1 or 0.12.0

Vendor Advisory: https://github.com/matrix-org/matrix-rust-sdk/security/advisories/GHSA-x958-rvg6-956w

Restart Required: Yes

Instructions:

1. Update matrix-sdk-crypto dependency to version 0.11.1 or 0.12.0
2. Rebuild and redeploy affected applications
3. Restart services using the updated library

🔧 Temporary Workarounds

Downgrade to pre-0.8.0

all

Revert to matrix-sdk-crypto version 0.7.x or earlier

cargo update -p matrix-sdk-crypto --precise 0.7.999

🧯 If You Can't Patch

Only connect to trusted homeservers with verified operator reputation
Implement additional client-side message verification and warn users about potential message tampering

🔍 How to Verify

Check if Vulnerable:

Check Cargo.toml or Cargo.lock for matrix-sdk-crypto version between 0.8.0 and 0.11.0 inclusive

Check Version:

grep -A2 -B2 'matrix-sdk-crypto' Cargo.lock

Verify Fix Applied:

Verify matrix-sdk-crypto version is 0.11.1 or higher in Cargo.lock

📡 Detection & Monitoring

Log Indicators:

Unexpected sender mismatches in encrypted events
Failed signature validations for encrypted messages

Network Indicators:

Modified event metadata in Matrix protocol traffic from untrusted servers

SIEM Query:

NOT_APPLICABLE

📊 Metadata

CVE ID: CVE-2025-48937

CVSS v3 Score: 4.9 (MEDIUM)

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

CWE: CWE-290

EPSS Score: 0.05% exploit probability (15.1th percentile)

Published: June 10, 2025

Last Updated: June 12, 2025

🔗 References

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🔗 Related Vulnerabilities

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