HMAC forgery via early-exit comparison
Published Jan 29, 2020 · Updated Aug 4, 2024
Timing discrepancy in Jenkins 2.218 and earlier and LTS 2.204.1 and earlier allows remote authenticated users to forge valid HMACs. The HMACConfidentialKey.checkMac methods compared calculated and supplied values with early-exit Arrays.equals and String.equals operations. Low-privilege network access and repeated timing measurements are required; a forged HMAC validates attacker-controlled input.
Summary
What happened
Timing discrepancy in Jenkins 2.218 and earlier and LTS 2.204.1 and earlier allows remote authenticated users to forge valid HMACs. The HMACConfidentialKey.checkMac methods compared calculated and supplied values with early-exit Arrays.equals and String.equals operations. Low-privilege network access and repeated timing measurements are required; a forged HMAC validates attacker-controlled input.
The record
- CVE
- CVE-2020-2102
- Published
- Jan 29, 2020
- Updated
- Aug 4, 2024
- Vendor
- Jenkins Project
- Product
- Jenkins
- Classifications
- CWE-208, CWE-203
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Jan 29, 2020CVE publishedPublication date reported by the CVE source.
- Aug 4, 2024Record 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=unspecified <=2.218
- Affected versionversion=unspecified <=LTS 2.204.1
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
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Public exploit references
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Technologies
Your stack
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Your stack
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