Non-constant time HMAC comparison
Jenkins 2.218 and earlier, LTS 2.204.1 and earlier does not use a constant-time comparison when checking whether two HMACs are equal. This could potentially allow attackers to use statistical methods to obtain a valid HMAC for an attacker-controlled input value. Jenkins 2.219, LTS 2.204.2 now uses a constant-time comparison when validating HMACs.
01
describes (1)
Related CVEs.
| ID | severity | exploitable | ||
|---|---|---|---|---|
| CVE-2020-2102US | medium5.3 | — | ||
Jenkins 2.218 and earlier, LTS 2.204.1 and earlier used a non-constant time comparison function when validating an HMAC. | ||||
02
references
External citations — patches, advisories, analysis.
- http://www.openwall.com/lists/oss-security/2020/01/29/1WEB
- https://access.redhat.com/errata/RHBA-2020:0402WEB
- https://access.redhat.com/errata/RHBA-2020:0675WEB
- https://access.redhat.com/errata/RHSA-2020:0681WEB
- https://access.redhat.com/errata/RHSA-2020:0683WEB
- https://github.com/jenkinsci/jenkinsPACKAGE
- https://github.com/jenkinsci/jenkins/commit/6f35dbb939ebe947bdb1979010b208480f1d0e31WEB
- https://jenkins.io/security/advisory/2020-01-29/#SECURITY-1660WEB
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