Full Report
Redis security advisory (AV26-859)
Analysis Summary
# Vulnerability: Redis Use-After-Free in TLS Pending Data Processing
## CVE Details
- **CVE ID:** CVE-2026-XXXXX (Specific ID not listed in the advisory; pending official assignment for the reported flaw).
- **CVSS Score:** Not specified in the advisory (Estimated High/Critical based on Use-After-Free nature).
- **CWE:** CWE-416 (Use After Free).
## Affected Systems
- **Products:** Redis
- **Versions:**
- 8.0
- All versions except: 8.10.1, 8.2.9, 8.4.6, 8.6.6, and 8.8.2.
- **Configurations:** Systems utilizing TLS (Transport Layer Security) for encrypted communications.
## Vulnerability Description
The vulnerability is a **Use-After-Free (UAF)** flaw located within the `tlsProcessPendingData()` function. This occurs during the iteration of the pending-list when processing TLS data. A UAF happens when a program continues to use a pointer after it has been freed, which can lead to memory corruption, unexpected behavior, or arbitrary code execution.
## Exploitation
- **Status:** Not explicitly stated as exploited in the wild; however, a fix has been committed to the public repository.
- **Complexity:** Medium (Requires specific timing/state during TLS handshake or data processing).
- **Attack Vector:** Network (Remote via TLS-enabled ports).
## Impact
- **Confidentiality:** High (Potential for memory disclosure).
- **Integrity:** High (Potential for memory corruption).
- **Availability:** High (Can lead to application crashes or Denial of Service).
## Remediation
### Patches
Users should upgrade to one of the following patched versions:
- Redis 8.10.1
- Redis 8.2.9
- Redis 8.4.6
- Redis 8.6.6
- Redis 8.8.2
### Workarounds
- If immediate patching is not possible, consider disabling TLS if the environment allows (e.g., using an alternative secure tunnel like IPSec or a VPN), though this is generally not recommended for production environments requiring transit encryption.
## Detection
- **Indicators of Compromise:** Monitor for unexpected crashes in the Redis process, specifically segmentation faults or memory-related errors associated with TLS operations.
- **Detection methods and tools:** Use memory sanitizers (like AddressSanitizer) in testing environments to catch UAF triggers. Monitor logs for anomalies in TLS handshake completions.
## References
- **Vendor Advisories:** hxxps[://]www[.]cyber[.]gc[.]ca/en/alerts-advisories/redis-security-advisory-av26-859
- **Relevant Links:**
- hxxps[://]github[.]com/redis/redis/commit/6d088c335d5c3ec49a6c28486140b498e70b7834
- hxxps[://]github[.]com/redis/redis/releases