SurrealDB memory exhaustion via string::replace using regex

An authenticated user can craft a query using the `string::replace` function that uses a Regex to perform a string replacement. As there is a failure to restrict the resulting string length, this enables an attacker to send a `string::replace` function to the SurrealDB server exhausting all the memory of the server due to string allocations. This eventually results in a Denial-of-Service situation for the SurrealDB server. This issue was discovered and patched during an code audit and penetration test of SurrealDB by cure53. Using CVSSv4 definitions, the severity is High. ### Impact An authenticated user can crash the SurrealDB instance through memory exhaustion ### Patches A patch has been created that enforces a limit on string length `SURREAL_GENERATION_ALLOCATION_LIMIT` - Versions 2.0.5, 2.1.5, 2.2.2, and later are not affected by this issue ### Workarounds Affected users who are unable to update may want to limit the ability of untrusted clients to run the `string::replace` function in the affected versions of SurrealDB using the `--deny-functions` flag described within [Capabilities](https://surrealdb.com/docs/surrealdb/security/capabilities#functions) or the equivalent `SURREAL_CAPS_DENY_FUNC` environment variable. ### References [SurrealQL Documentation - DB Functions (string::replace)](https://surrealdb.com/docs/surrealql/functions/database/string#stringreplace) [SurrealDB Documentation - Capabilities](https://surrealdb.com/docs/surrealdb/security/capabilities#functions) [SurrealDB Documentation - Environment Variables](https://surrealdb.com/docs/surrealdb/cli/env) [#5619 ](https://github.com/surrealdb/surrealdb/pull/5619) [#5638 ](https://github.com/surrealdb/surrealdb/pull/5638)

Source published

11 Apr 2025 14:08:03 UTC

Source modified

19 Jul 2026 03:56:48 UTC

Observed here

24 Oct 2026 13:19:54 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Publisher rating · HIGH