Cross-origin data disclosure via unescaped allowlist regex
Published Feb 9, 2026 · Updated Feb 9, 2026
Cross-origin policy bypass in Litestar before 2.20.0 allows remote attackers to read protected responses through a victim's browser. CORSConfig.allowed_origins_regex joins configured origins into a regular expression without escaping metacharacters, so fullmatch() accepts lookalike attacker origins. Exposure requires a restrictive CORS allowlist and a victim visiting an attacker-controlled site; credentialed CORS can disclose authenticated response data.
Summary
What happened
Cross-origin policy bypass in Litestar before 2.20.0 allows remote attackers to read protected responses through a victim's browser. CORSConfig.allowed_origins_regex joins configured origins into a regular expression without escaping metacharacters, so fullmatch() accepts lookalike attacker origins. Exposure requires a restrictive CORS allowlist and a victim visiting an attacker-controlled site; credentialed CORS can disclose authenticated response data.
The record
- CVE
- CVE-2026-25478
- Published
- Feb 9, 2026
- Updated
- Feb 9, 2026
- Vendor
- Litestar
- Product
- Litestar
- Classifications
- CWE-942
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Feb 9, 2026CVE publishedPublication date reported by the CVE source.
- Feb 9, 2026Record 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.
- Affected versionversion=< 2.20.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
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.
Weakness, pattern, technique
Public exploit references
- GHSA-2p2x-hpg8-cqp2 proof of conceptproof of concept · demonstrated
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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