# CVE-2026-88410: FalkorDB graph.UDF write flag missing and uninterruptible execution

Source: https://junglewise.ai/threats/cve-2026-88410-the-graph-udf-in-falkordb-redis-module-v4-20-1-to-v4-20-4-is-not  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-21. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-88410 · Severity: high · CVSS 7.1 · Published 2026-09-21

FalkorDB, a Redis module for graph databases, has multiple security defects in its user-defined function (UDF) feature. An authenticated user can register JavaScript code that hangs worker threads indefinitely with no way to stop it, and UDF registrations bypass write-command protections, potentially causing replica divergence. Additionally, corrupted RDB files can cause silent library loss or buffer underflows during recovery.

Technologies: [FalkorDB](https://junglewise.ai/threats/technologies/falkordb). Vendors: [FalkorDB](https://junglewise.ai/threats/vendors/falkordb).

## Quick answers

**Is CVE-2026-88410 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-88410 being exploited in the wild.

**How severe is CVE-2026-88410?** High severity, with a CVSS score of 7.1, published 21 September 2026.

**Which products and versions are affected?** FalkorDB 4.20.1 to 4.20.4.

**Is there a fix for CVE-2026-88410?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-88410 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-88410?** Check whether you run FalkorDB at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The graph.UDF command is not registered as a write operation despite mutating persistent state and being written to RDB, bypassing replica write restrictions and deny-oom checks. The RDB decoder uses unchecked ASSERT() statements that compile out in release builds, causing malformed UDF data to be silently skipped; additionally, zero-length string buffers trigger size_t underflow. An authenticated attacker can register a UDF containing an infinite loop to permanently hang a worker thread, as the QuickJS runtime lacks an interrupt handler and timeout mechanism comparable to Redis's SCRIPT KILL.

## Affected products

- FalkorDB FalkorDB 4.20.1 to 4.20.4

## Timeline

- 2026-09-21: disclosed

## References

- [https://github.com/FalkorDB/FalkorDB/issues/2401](https://github.com/FalkorDB/FalkorDB/issues/2401)

## Related threats

- [FalkorDB type confusion in _read_flags function](https://junglewise.ai/threats/cve-2026-107911-a-type-confusion-vulnerability-in-the-read-flags-function-src)
- [FalkorDB improper authentication in Bolt endpoint](https://junglewise.ai/threats/cve-2026-107910-an-improper-authentication-vulnerability-in-the-is-authenticated)
- [FalkorDB heap-based buffer overflow in WebSocket frame handling](https://junglewise.ai/threats/cve-2026-107909-a-heap-based-out-of-bounds-write-in-the-ws-read-frame-function)
- [FalkorDB heap-based buffer overflow in Bolt handler](https://junglewise.ai/threats/cve-2026-107908-a-heap-based-out-of-bounds-write-in-the-boltreadhandler-function)
- [FalkorDB stack-based buffer overflow in RDB graph entity decoder](https://junglewise.ai/threats/cve-2026-7827-a-stack-based-buffer-overflow-in-the-rdbloadentity-function-of-the)