Authentication token forgery via reused Poly1305 key
Published Mar 5, 2021 · Updated Aug 4, 2024
Cryptographic verification failure in ScottBrady.IdentityModel before 1.3.0 allows remote attackers to modify and forge Branca tokens. BrancaTokenHandler initializes Poly1305 directly with the long-lived symmetric key, reusing a one-time authenticator key across tokens instead of deriving it per nonce. An attacker who obtains multiple tokens under the same symmetric key can forge a valid tag and alter authenticated token claims.
Summary
What happened
Cryptographic verification failure in ScottBrady.IdentityModel before 1.3.0 allows remote attackers to modify and forge Branca tokens. BrancaTokenHandler initializes Poly1305 directly with the long-lived symmetric key, reusing a one-time authenticator key across tokens instead of deriving it per nonce. An attacker who obtains multiple tokens under the same symmetric key can forge a valid tag and alter authenticated token claims.
The record
- CVE
- CVE-2020-36255
- Published
- Mar 5, 2021
- Updated
- Aug 4, 2024
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- T1606
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Mar 5, 2021CVE publishedPublication date reported by the CVE source.
- Aug 4, 2024Record updatedLatest update available in the CVE record.
Exploitability
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What is affected?
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Attacks
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Technologies
Your stack
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