CVE-2026-107909 Pre-authentication heap out-of-bounds write in FalkorDB Bolt WebSocket frame handling via unbounded payload length
Remote unauthenticated attackers can cause denial of service or potential code execution via heap corruption in FalkorDB's Bolt WebSocket handling when the Bolt endpoint is enabled.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-107909?
CVE-2026-107909 is a high-severity memory corruption vulnerability in FalkorDB, published on 9 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A heap-based out-of-bounds write in the ws_read_frame function (src/bolt/ws.c) and the buffer_apply_mask function (src/bolt/buffer.c) in FalkorDB before 4.20.0 allows a remote unauthenticated attacker to cause a denial of service and possibly corrupt heap memory by sending a WebSocket frame with a 64-bit extended payload length to the Bolt port. The payload length is not bounded, and the only bounds check in buffer_apply_mask is an ASSERT(), which is compiled out in release builds, so the function XORs memory beyond the end of the receive buffer with the attacker-supplied mask key. Only deployments that enable the Bolt endpoint (BOLT_PORT, disabled by default) are affected.
Weakness: CWE-787
Which versions are affected by CVE-2026-107909?
How do I fix CVE-2026-107909?
No fix has been published for CVE-2026-107909 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-107909 being exploited?
There is no known exploitation of CVE-2026-107909 in the wild and no public exploit code.
Sources
Also known as GHSA-x67x-q5pm-p9h7.