RHSA-2026:27738 - Security Advisory

Topic

An update for libpq is now available for Red Hat Enterprise Linux 8.

Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.

Description

The libpq package provides the PostgreSQL client library, which allows client programs to connect to PostgreSQL servers.

Security Fix(es):

• postgresql: PostgreSQL: Operating system account hijack via symlink following in pg_basebackup and pg_rewind (CVE-2026-6475)
• postgresql: PostgreSQL libpq: Buffer overflow allows server superuser to overwrite client stack memory (CVE-2026-6477)
• postgresql: PostgreSQL: Credential recovery via covert timing channel in MD5 password comparison (CVE-2026-6478)
• postgresql: integer overflow can cause an undersized allocation and an out-of-bounds write (CVE-2026-6473)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Solution

For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

Affected Products

• Red Hat Enterprise Linux for x86_64 8 x86_64
• Red Hat Enterprise Linux for IBM z Systems 8 s390x
• Red Hat Enterprise Linux for Power, little endian 8 ppc64le
• Red Hat Enterprise Linux for ARM 64 8 aarch64
• Red Hat Enterprise Linux for x86_64 - Extended Life Cycle 8.10 x86_64
• Red Hat Enterprise Linux for ARM 64 - Extended Life Cycle 8.10 aarch64
• Red Hat Enterprise Linux for Power, little endian - Extended Life Cycle 8.10 ppc64le
• Red Hat Enterprise Linux for IBM z Systems - Extended Life Cycle 8.10 s390x

Fixes

• BZ - 2477439 - CVE-2026-6475 postgresql: PostgreSQL: Operating system account hijack via symlink following in pg_basebackup and pg_rewind
• BZ - 2477442 - CVE-2026-6477 postgresql: PostgreSQL libpq: Buffer overflow allows server superuser to overwrite client stack memory
• BZ - 2477447 - CVE-2026-6478 postgresql: PostgreSQL: Credential recovery via covert timing channel in MD5 password comparison
• BZ - 2477448 - CVE-2026-6473 postgresql: integer overflow can cause an undersized allocation and an out-of-bounds write

CVEs

• CVE-2026-6473
• CVE-2026-6475
• CVE-2026-6477
• CVE-2026-6478

References

• https://access.redhat.com/security/updates/classification/#important