Authorization bypass via SSH public-key HMAC confusion
Published May 24, 2022 · Updated Apr 23, 2025
Key confusion in PyJWT 1.5.0 through 2.3.0 allows remote attackers to forge accepted JWTs using a public key as an HMAC secret. HMACAlgorithm.prepare_key rejects only a short list of asymmetric-key prefixes and accepts SSH Ed25519 or ECDSA public-key formats as symmetric secrets. Exploitation requires an application to enable both asymmetric and HMAC algorithms, such as get_default_algorithms(), and can bypass token-based authorization.
Summary
What happened
Key confusion in PyJWT 1.5.0 through 2.3.0 allows remote attackers to forge accepted JWTs using a public key as an HMAC secret. HMACAlgorithm.prepare_key rejects only a short list of asymmetric-key prefixes and accepts SSH Ed25519 or ECDSA public-key formats as symmetric secrets. Exploitation requires an application to enable both asymmetric and HMAC algorithms, such as get_default_algorithms(), and can bypass token-based authorization.
The record
- CVE
- CVE-2022-29217
- Published
- May 24, 2022
- Updated
- Apr 23, 2025
- Vendor
- Jose Padilla
- Product
- PyJWT
- Classifications
- CWE-327, T1550.001
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 24, 2022CVE publishedPublication date reported by the CVE source.
- Apr 23, 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=>= 1.5.0, < 2.4.0
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
- SSH public-key HMAC confusion 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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