CVE-2023-51437: Apache Pulsar: Timing attack in SASL token signature verification

Severity: high (CVSS 7.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.8% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-02-07 · updated 2026-06-17
Weakness: CWE-203

Description

Observable timing discrepancy vulnerability in Apache Pulsar SASL Authentication Provider can allow an attacker to forge a SASL Role Token that will pass signature verification. Users are recommended to upgrade to version 2.11.3, 3.0.2, or 3.1.1 which fixes the issue. Users should also consider updating the configured secret in the `saslJaasServerRoleTokenSignerSecretPath` file. Any component matching an above version running the SASL Authentication Provider is affected. That includes the Pulsar Broker, Proxy, Websocket Proxy, or Function Worker. 2.11 Pulsar users should upgrade to at least 2.11.3. 3.0 Pulsar users should upgrade to at least 3.0.2. 3.1 Pulsar users should upgrade to at least 3.1.1. Any users running Pulsar 2.8, 2.9, 2.10, and earlier should upgrade to one of the above patched versions. For additional details on this attack vector, please refer to https://codahale.com/a-lesson-in-timing-attacks/ .

Affected products

Apache Software Foundation Apache Pulsar: through 2.10.5; from 2.11.0 before 2.11.3; from 3.0.0 before 3.0.2; 3.1.0, 3.1.0-candidate_1 — fixed in 2.11.3, 3.0.2

How to fix

Upgrade to a fixed version: Apache Software Foundation Apache Pulsar 2.11.3, 3.0.2. Check the vendor advisory for mitigations.

References

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