CVE-2025-68704: Jervis Timing Attack Vulnerability

CVE-2025-68704 Overview

CVE-2025-68704 is an Insecure Random Number Generation vulnerability affecting Jervis, a library for Job DSL plugin scripts and shared Jenkins pipeline libraries. Prior to version 2.2, Jervis uses java.util.Random() which is not cryptographically secure for timing attack mitigation. This weakness (CWE-330: Use of Insufficiently Random Values) can allow attackers to predict random values and potentially exploit timing attack mitigations implemented within the library.

Critical Impact

The use of a non-cryptographically secure random number generator undermines timing attack protections, potentially exposing sensitive operations to side-channel attacks in Jenkins CI/CD environments.

Affected Products

• Jervis library versions prior to 2.2
• Jenkins environments utilizing Jervis for Job DSL plugin scripts
• Jenkins shared pipeline libraries built with vulnerable Jervis versions

Discovery Timeline

• 2026-01-13 - CVE CVE-2025-68704 published to NVD
• 2026-01-13 - Last updated in NVD database

Technical Details for CVE-2025-68704

Vulnerability Analysis

The vulnerability stems from the use of java.util.Random() in Jervis, a pseudorandom number generator (PRNG) that is not suitable for cryptographic or security-sensitive operations. When used for timing attack mitigation, such as introducing random delays to obscure processing time differences, the predictability of java.util.Random() undermines the intended protection.

The java.util.Random() class uses a linear congruential generator (LCG) algorithm with a 48-bit seed. Given enough observations of the output, an attacker can reconstruct the internal state and predict future values. This predictability is especially dangerous in security contexts where randomness is relied upon to prevent information leakage.

Root Cause

The root cause is the selection of an inappropriate random number generator for security-critical functionality. The CWE-330 (Use of Insufficiently Random Values) classification highlights that the generated values lack sufficient entropy and unpredictability. In Java, java.util.Random() should be replaced with java.security.SecureRandom for any security-sensitive operations, including timing attack countermeasures.

Attack Vector

The attack vector is network-based with high complexity requirements. An attacker with network access to a Jenkins instance running vulnerable Jervis versions could potentially:

1. Observe timing variations in operations protected by the weak random delays
2. Collect sufficient samples to predict the PRNG output sequence
3. Use the predicted values to bypass timing attack mitigations
4. Exploit the underlying timing side-channel to extract sensitive information

The vulnerability affects operations where Jervis introduces random delays to mask processing time differences that could otherwise reveal information about the data being processed.

The fix involves replacing java.util.Random() with a cryptographically secure alternative such as java.security.SecureRandom. For detailed implementation changes, see the GitHub commit that addresses this vulnerability.

Detection Methods for CVE-2025-68704

Indicators of Compromise

• Jervis library versions below 2.2 present in Jenkins installations
• Presence of java.util.Random() calls in security-sensitive code paths within Jervis-dependent pipelines
• Unusual patterns of repeated requests that may indicate timing analysis attempts

Detection Strategies

• Audit Jenkins plugin dependencies for Jervis versions prior to 2.2
• Scan shared pipeline libraries for vulnerable Jervis imports
• Implement Software Composition Analysis (SCA) tools to identify vulnerable library versions
• Review Jenkins logs for patterns consistent with timing attack reconnaissance

Monitoring Recommendations

• Monitor Jenkins pipeline execution for anomalous timing request patterns
• Configure alerting for dependency scanning results indicating vulnerable Jervis versions
• Track access patterns to Jenkins endpoints that utilize Jervis functionality
• Implement network monitoring for repeated requests with systematic timing variations

How to Mitigate CVE-2025-68704

Immediate Actions Required

• Upgrade Jervis library to version 2.2 or later immediately
• Audit all Jenkins installations for vulnerable Jervis dependencies
• Review shared pipeline libraries that may be using affected versions
• Consider temporarily disabling affected pipelines until patching is complete

Patch Information

The vulnerability is fixed in Jervis version 2.2. The patch replaces the insecure java.util.Random() with a cryptographically secure random number generator. Organizations should update their Jervis dependencies to version 2.2 or later.

For detailed patch information, refer to the GitHub Security Advisory GHSA-c9q6-g3hr-8gww and the commit with the fix.

Workarounds

• If immediate upgrade is not possible, consider implementing additional timing attack protections at the application layer
• Restrict network access to Jenkins instances to reduce exposure
• Implement rate limiting on sensitive endpoints to make timing attacks more difficult
• Monitor for exploitation attempts while preparing for the upgrade

# Update Jervis dependency in your build configuration
# For Gradle (build.gradle):
# implementation 'net.gleske:jervis:2.2'

# For Maven (pom.xml):
# <dependency>
#   <groupId>net.gleske</groupId>
#   <artifactId>jervis</artifactId>
#   <version>2.2</version>
# </dependency>