CVE-2025-54365Public exploitNetwork attack vector

Request-filter bypass via overlong script-tag attributes

Published Jul 23, 2025 · Updated Jul 24, 2025

Input-validation bypass in FastAPI Guard 3.0.1 allows remote attackers to evade request filtering with crafted script-tag attributes. The detect_penetration_attempt function uses bounded regex quantifiers that stop matching when a script tag's attributes exceed 100 characters. An unauthenticated request reaching a protected application route can therefore pass malicious input that the configured patterns were intended to reject.

CVSS severityUnavailable
Unscored
EPSS probability0.73%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Input-validation bypass in FastAPI Guard 3.0.1 allows remote attackers to evade request filtering with crafted script-tag attributes. The detect_penetration_attempt function uses bounded regex quantifiers that stop matching when a script tag's attributes exceed 100 characters. An unauthenticated request reaching a protected application route can therefore pass malicious input that the configured patterns were intended to reject.

The record

CVE
CVE-2025-54365
Published
Jul 23, 2025
Updated
Jul 24, 2025
Vendor
Renzo Franceschini
Product
FastAPI Guard
Classifications
CWE-185, CWE-20, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 23, 2025CVE publishedPublication date reported by the CVE source.
  2. Jul 24, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 3.0.1, < 3.0.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Renzo Franceschini · FastAPI Guardversion=>= 3.0.1, < 3.0.2

Published CVSS scores

7.8GitHub CNACVSS: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

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-185Incorrect Regular Expression
CWE-20Improper Input Validation
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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