Vulnerability · Published Jul 23, 2025 · Assigned by GitHub_M
CVE-2025-54365fastapi-guard patch contains bypassable RegEx
High 7.8
In plain English
A high-severity improper input validation in fastapi-guard from rennf93. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.9% (higher than 59% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
fastapi-guard is a security library for FastAPI that provides middleware to control IPs, log requests, detect penetration attempts and more. In version 3.0.1, the regular expression patched to mitigate the ReDoS vulnerability by limiting the length of string fails to catch inputs that exceed this limit. This type of patch fails to detect cases in which the string representing the attributes of a <script> tag exceeds 100 characters. As a result, most of the regex patterns present in version 3.0.1 can be bypassed. This is fixed in version 3.0.2.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| PyPI | fastapi-guard | 3.0.2 | GHSA-rrf6-pxg8-684g |
| PyPI | fastapi-guard | 3.0.2 | PYSEC-2026-1360 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| rennf93 | fastapi-guard | >= 3.0.1, < 3.0.2 |
Weakness: CWE-20, CWE-185 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N/E:P
References
- https://github.com/rennf93/fastapi-guard/security/advisories/GHSA-rrf6-pxg8-684g x_refsource_CONFIRM
- https://github.com/rennf93/fastapi-guard/commit/0829292c322d33dc14ab00c5451c5c138148035a x_refsource_MISC
- https://github.com/rennf93/fastapi-guard/commit/d9d50e8130b7b434cdc1b001b8cfd03a06729f7f x_refsource_MISC