Algorithm Downgrade in Postgresql JDBC Driver - CVE-2026-54291

Vulnerability identifier: #VU135919

CSH Severity: Medium

CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-54291

CWE-ID: CWE-757

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to bypass channel-binding protection and enable a man-in-the-middle downgrade of authentication.

The vulnerability exists due to failing open and algorithm downgrade in ScramAuthenticator when processing certificates whose signature algorithm has no tls-server-end-point channel-binding hash. A remote attacker can present a certificate with an unsupported signature algorithm while intercepting the TLS connection to bypass channel-binding protection and enable a man-in-the-middle downgrade of authentication.

Only connections configured with channelBinding=require are affected.

Postgresql JDBC Driver
IBM Watson Speech Services Cartridge for IBM Cloud Pak for Data
Crucible Data Center
Crucible Server
Crowd Data Center
Bitbucket Data Center
Confluence Data Center
Jira Software Data Center
Bamboo Data Center
Jira Service Management Data Center
Maximo Application Suite - IoT Component

Install security update from vendor's website.

Postgresql JDBC Driver - update to 42.7.12
IBM Watson Speech Services Cartridge for IBM Cloud Pak for Data - update to 5.4.0 Patch 3
Crucible Data Center - update to 4.9.12
Crucible Server - update to 4.9.12
Crowd Data Center - update to 7.2.2
Maximo Application Suite - IoT Component - addressed in versions 9.0.22, 9.1.13, 9.2.1
Bitbucket Data Center - update to 9.4.8
Confluence Data Center - addressed in versions 9.2.11, 10.2.0
Jira Software Data Center - addressed in versions 9.12.38, 10.3.24, 11.3.9
Bamboo Data Center - addressed in versions 10.2.22, 12.1.10
Jira Service Management Data Center - addressed in versions 10.3.24, 11.3.10

• https://github.com/pgjdbc/pgjdbc/security/advisories/GHSA-j92g-9f8w-j867
• https://github.com/pgjdbc/pgjdbc/commit/77df98e4e66c12936ded3478a0954f6f580bad99

• Algorithm Downgrade in Postgresql JDBC Driver
• IBM Watson Speech Services Cartridge update for pgjdbc
• Multiple vulnerabilities in IBM Maximo Application Suite - IoT Component
• Multiple vulnerabilities in Bamboo Data Center
• Algorithm Downgrade in Bitbucket Data Center
• Algorithm Downgrade in Confluence Data Center
• Algorithm Downgrade in Crucible Data Center and Crucible Server
• Multiple vulnerabilities in Crowd Data Center
• Multiple vulnerabilities in Jira Service Management Data Center
• Multiple vulnerabilities in Jira Software Data Center