Secuno
ENNL
Book demo

CVE-2025-53539

Fastapi-guard Fastapi Guard vulnerability

7.5 HIGHPublic exploitEPSS 0.45%
  1. Published7 Jul 2025

Description

FastAPI Guard is a security library for FastAPI that provides middleware to control IPs, log requests, and detect penetration attempts. fastapi-guard's penetration attempts detection uses regex to scan incoming requests. However, some of the regex patterns used in detection are extremely inefficient and can cause polynomial complexity backtracks when handling specially crafted inputs. This vulnerability is fixed in 3.0.1.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityNone
IntegrityNone
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

Fastapi-guard Fastapi Guard< 3.0.1

Remediation

Fixed in
Fastapi-guard Fastapi Guard≥ 3.0.1

References

Related CVEs

Recent high-severity vulnerabilities sharing a weakness type.

CVE-2026-826179.8
The two built-in name-finder patterns exposed by…
CVE-2026-527789.8
YesWiki is a wiki system written in PHP. Prior to version 4.6.6, an unsafe execution…
CVE-2026-354589.8
Gotenberg is an API for converting document formats. In 8.29.1 and earlier, Gotenberg…
CVE-2025-624848.1
Inefficient regular expression complexity in certain Zoom Workplace Clients before…

Frequently asked

Is CVE-2025-53539 being actively exploited?

CVE-2025-53539 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.45%.

How severe is CVE-2025-53539?

CVE-2025-53539 has a CVSS 3.1 base score of 7.5, rated high. EPSS estimates a 0.45% probability of exploitation.

Which products are affected by CVE-2025-53539?

Affected products include Fastapi-guard Fastapi Guard.

How do I fix CVE-2025-53539?

Upgrade affected software to a fixed version, for example Fastapi-guard Fastapi Guard 3.0.1 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2025-53539 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

See how prioritisation worksBook a demo

Get Patch this first every Monday

Five vulnerabilities that matter this week, ranked on real exploitation. Plain language, one email, no spam.

You can unsubscribe with one click from every issue. We handle your details as described in our privacy policy.

Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.