Redis has patched a use-after-free in its blocking-client code that lets an authenticated user run arbitrary OS commands on the machine hosting the database. The flaw was found by an autonomous AI tool built to hunt bugs in large codebases.
Tracked as CVE-2026-23479, the flaw was introduced in Redis 7.2.0 and remained in every stable branch until the May 5 fixes, unnoticed for over two years. NVD rates it 8.8 under CVSS 3.1; Redis lists it as 7.7 under CVSS 4.0. It was reported by Team Xint Code, and a complete technical write-up is now public.
The cloud footprint makes this worse. Wiz's analysis, published with the exploit writeup, puts Redis in a large majority of cloud environments, with most of those instances running without a password. The exploit needs an authenticated session, but in a default deployment, the default user already holds every privilege the chain requires.
The flaw lives in unblockClientOnKey() in src/blocked.c, which fires when a key event wakes a blocked command. The function dispatches the queued command through processCommandAndResetClient(), then keeps using the same client pointer. The problem: that function can free the client as a side effect, and its own header comment says so. The caller ignores the return value and reads the freed structure anyway, a use-after-free (CWE-416).
