RediShell
- Product
- Redis Redis (Lua scripting engine), also Valkey and managed Redis services
- CVE
- CVE-2025-49844
- Disclosed
- 2025-10-03
- CVSS
- 9.9
- Auth
- requires auth / interaction
- CISA KEV
- no
- Affected
- All Redis versions with Lua scripting up to 8.2.1 (bug ~13 years old)
- Fixed
- Redis OSS/CE 8.2.2 (plus backports 8.0.4, 7.4.6, 7.2.11); Redis Stack 7.4.0-v7 / 7.2.0-v19; Redis Software 7.22.2-20 (and backports); Valkey patched the same day
Summary
Wiz Research found a use-after-free in Redis's embedded Lua interpreter, first shown at Pwn2Own Berlin 2025. An authenticated user who can run EVAL can escape the Lua sandbox and execute native code on the host. Because many Redis instances run without a password, 'authenticated' often means 'anyone who can connect'.
Root cause
A crafted Lua script can manipulate the garbage collector so that an object is freed while the parser still holds a reference to it, giving a use-after-free in Redis's bundled Lua. With that memory corruption the attacker escapes the Lua sandbox and gets arbitrary native code execution in the redis-server process.
Impact
Remote code execution as the Redis process; on exposed no-auth instances this is effectively unauthenticated.
Detection
Check redis-server version (INFO server); look for unusual EVAL/EVALSHA usage from untrusted clients. Wiz and vendors published version-based checks.
Mitigation
Upgrade Redis/Valkey; require authentication, keep Redis off the internet, and block EVAL/EVALSHA via ACLs for users that do not need scripting.