CSRF bypass via unbound cookie tokens
Published Apr 20, 2023 · Updated Feb 5, 2025
CSRF bypass in Fastify @fastify/csrf-protection before 4.1.0 and 5.0.0 through 6.2.0 allows remote attackers to submit forged requests. The cookie-backed token path accepts a missing or predictable userInfo value without a server-secret HMAC, enabling fixation of the _csrf cookie and token generation for a victim session. Exploitation requires @fastify/cookie, a predictable or absent user binding, same-site or network access, and user interaction; successful requests can perform the application's protected state changes.
Summary
What happened
CSRF bypass in Fastify @fastify/csrf-protection before 4.1.0 and 5.0.0 through 6.2.0 allows remote attackers to submit forged requests. The cookie-backed token path accepts a missing or predictable userInfo value without a server-secret HMAC, enabling fixation of the _csrf cookie and token generation for a victim session. Exploitation requires @fastify/cookie, a predictable or absent user binding, same-site or network access, and user interaction; successful requests can perform the application's protected state changes.
The record
- CVE
- CVE-2023-27495
- Published
- Apr 20, 2023
- Updated
- Feb 5, 2025
- Vendor
- Fastify
- Product
- @fastify/csrf-protection
- Classifications
- CWE-352, CAPEC-62
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Apr 20, 2023CVE publishedPublication date reported by the CVE source.
- Feb 5, 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.
- Affected versionversion=< 4.1.0
- Affected versionversion=>= 5.0.0, < 6.3.0
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
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Technologies
Your stack
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Your stack
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