[Security] Two unsynced Redis silent security fixes affecting KeyDB

Summary

KeyDB's source contains two security vulnerabilities that were silently fixed in Redis upstream (no CVE, no GHSA — discovered via commit log analysis). The fixes have not been ported to KeyDB.

Issue 1: Use-After-Free in RM_RegisterClusterMessageReceiver

Severity: HIGH (UAF, module-triggered) Location: src/module.cpp line 6225 Redis fix: commit 303667a40cdf5032b1044e94dfc6860a15414e03 (Apr 23 2026)

When a module unregisters a cluster message receiver (callback = NULL), removing the head node updates the wrong pointer:

// src/module.cpp:6222-6225 (vulnerable)
if (prev)
    prev->next = r->next;
else
    clusterReceivers[type]->next = r->next;   // BUG
zfree(r);

After zfree(r), clusterReceivers[type] still points to freed memory. Any subsequent traversal dereferences a dangling pointer.

Fix: Change clusterReceivers[type]->next = r->next; to clusterReceivers[type] = r->next;

Issue 2: Sentinel Config Injection via SENTINEL SET

Severity: HIGH (Code execution via config injection on Sentinel restart) Location: src/sentinel.cpp sentinelSetCommand() line ~4001, especially auth-pass (4084-4089), auth-user (4090-4095), notification-script (4055-4063), client-reconfig-script (4064-4083) Redis fix: commit 3e1afec688dc3f9354277ce6ad522996ebe4f2a6 (May 5 2026) Type: CWE-93 → CWE-94

KeyDB's SENTINEL SET handler accepts arbitrary control characters (including \r\n) in user-controlled string fields and persists them to the Sentinel config file without escaping. An authenticated attacker with SENTINEL SET access can inject arbitrary config directives:

SENTINEL SET mymaster auth-pass "secret\\r\\nnotification-script /tmp/evil.sh"

On next Sentinel restart, the persisted config contains an injected notification-script line, which executes during failover events.

Fix path (from Redis):

1. Add sentinelStringContainsControlChars() — reject 0x00-0x1F and 0x7F at SENTINEL SET / MONITOR / CONFIG SET entry points
2. Add sentinelSdscatConfigArg() — use sdscatrepr when a value needs escaping (defense in depth)

References

• Redis silent fix 303667a40: https://github.com/redis/redis/commit/303667a40
• Redis silent fix 3e1afec68: https://github.com/redis/redis/commit/3e1afec68

Note: Reporting on GitHub since KeyDB has no SECURITY.md. Please advise if private channel preferred.