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Non-constant time HMAC comparison

Moderate severity GitHub Reviewed Published May 24, 2022 to the GitHub Advisory Database • Updated Dec 13, 2023

Package

maven org.jenkins-ci.main:jenkins-core (Maven)

Affected versions

<= 2.204.1
>= 2.205, <= 2.218

Patched versions

2.204.2
2.219

Description

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.

References

Published by the National Vulnerability Database Jan 29, 2020
Published to the GitHub Advisory Database May 24, 2022
Reviewed Dec 19, 2022
Last updated Dec 13, 2023

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N

EPSS score

0.199%
(58th percentile)

Weaknesses

CVE ID

CVE-2020-2102

GHSA ID

GHSA-fj6f-6933-839j

Source code

Credits

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