CVE-2026-109338: SurrealDB denial of service via non-ASCII header values

CVE-2026-109338 · Severity: medium · CVSS 6.5 · Published 2026-10-12

SurrealDB is a database platform with embedded scripting capabilities. When scripting is enabled, a user with query permissions can crash the entire server by reading HTTP header values that contain non-ASCII characters, causing a denial of service affecting all databases on the instance until restart. Only servers with the --allow-scripting flag enabled are vulnerable.

Technologies: Surrealdb. Vendors: SurrealDB.

Quick answers

Is CVE-2026-109338 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-109338 being exploited in the wild.
How severe is CVE-2026-109338?
Medium severity, with a CVSS score of 6.5, published 12 October 2026.
Which products and versions are affected?
Surrealdb before 3.3.0.
Is there a fix for CVE-2026-109338?
Yes: fixed in 3.3.0. Until then: Leave embedded scripting disabled (the default). If scripting is enabled, restrict network access via --deny-net to trusted endpoints, limit who can write scripts by disabling guest access and using --deny-arbitrary-query, and run SurrealDB under a process manager that automatically restarts on crash (such as Kubernetes or systemd with Restart=on-failure). Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-109338 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-109338?
Check whether you run Surrealdb 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.

How to fix

  • Fixed in: 3.3.0

Leave embedded scripting disabled (the default). If scripting is enabled, restrict network access via --deny-net to trusted endpoints, limit who can write scripts by disabling guest access and using --deny-arbitrary-query, and run SurrealDB under a process manager that automatically restarts on crash (such as Kubernetes or systemd with Restart=on-failure).

Technical details

An uncaught panic occurs in the JavaScript Headers class when accessing header values containing non-ASCII bytes. The vulnerable code assumes header values are plain ASCII and panics on non-ASCII input. An attacker with query execution privileges can trigger this via Headers.get(), entries(), values(), or getSetCookie() on a Headers object, or by reading response headers from a fetch() call. The fix decodes non-ASCII values as UTF-8, treating invalid sequences as U+FFFD.

Affected products

  • SurrealDB SurrealDB before 3.3.0

Timeline

  • 2026-09-28: disclosed
  • 2026-09-28: patched: Version 3.3.0
  • 2026-10-12: advisory

References

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