Timing attack in SASL token signature verification in Apache Pulsar

Published: 2024-02-12
Risk High
Patch available YES
Number of vulnerabilities 1
CVE-ID CVE-2023-51437
Exploitation vector Network
Public exploit N/A
Vulnerable software
Apache Pulsar
Server applications / Conferencing, Collaboration and VoIP solutions

Vendor Apache Foundation

Security Bulletin

This security bulletin contains one high risk vulnerability.

1) Observable discrepancy

EUVDB-ID: #VU86330

Risk: High

CVSSv3.1: 7.9 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2023-51437

CWE-ID: CWE-203 - Observable discrepancy

Exploit availability: No


The vulnerability allows a remote attacker to bypass authentication.

The vulnerability exists due to observable timing discrepancy in SASL authentication provider. A remote attacker can forge a SASL Role Token that will pass signature verification and bypass SASL authentication.


Install updates from vendor's website.

Vulnerable software versions

Apache Pulsar: 2.0.0 - 3.1.0

External links


Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.