RHSA-2026:18683 - Security Advisory

Topic

An update for libssh is now available for Red Hat Enterprise Linux 9.

Red Hat Product Security has rated this update as having a security impact of Moderate. 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

libssh is a library which implements the SSH protocol. It can be used to implement client and server applications.

Security Fix(es):

• libssh: Double Free Vulnerability in libssh Key Export Functions (CVE-2025-5351)
• libssh: Use of uninitialized variable in privatekey_from_file() (CVE-2025-4878)
• libssh: Write beyond bounds in binary to base64 conversion functions (CVE-2025-4877)
• libssh: NULL Pointer Dereference in libssh KEX Session ID Calculation (CVE-2025-8114)
• libssh: Memory Exhaustion via Repeated Key Exchange in libssh (CVE-2025-8277)
• libssh: Buffer underflow in ssh_get_hexa() on invalid input (CVE-2026-0966)
• libssh: Improper sanitation of paths received from SCP servers (CVE-2026-0964)
• libssh: libssh: Denial of Service via improper configuration file handling (CVE-2026-0965)
• libssh: libssh: Denial of Service via inefficient regular expression processing (CVE-2026-0967)
• libssh: libssh: Denial of Service due to malformed SFTP message (CVE-2026-0968)

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.

Additional Changes:

For detailed information on changes in this release, see the Red Hat Enterprise Linux 9 Release Notes linked from 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 9 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 9.8 x86_64
• Red Hat Enterprise Linux for IBM z Systems 9 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 9.8 s390x
• Red Hat Enterprise Linux for Power, little endian 9 ppc64le
• Red Hat Enterprise Linux for Power, little endian - Extended Update Support 9.8 ppc64le
• Red Hat Enterprise Linux for ARM 64 9 aarch64
• Red Hat Enterprise Linux for ARM 64 - Extended Update Support 9.8 aarch64
• Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions 9.8 ppc64le
• Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 9.8 x86_64
• Red Hat Enterprise Linux for ARM 64 - 4 years of updates 9.8 aarch64
• Red Hat Enterprise Linux for IBM z Systems - 4 years of updates 9.8 s390x
• Red Hat Enterprise Linux for x86_64 - Extended Life Cycle 9.8 x86_64
• Red Hat Enterprise Linux for ARM 64 - Extended Life Cycle 9.8 aarch64
• Red Hat Enterprise Linux for Power, little endian - Extended Life Cycle 9.8 ppc64le
• Red Hat Enterprise Linux for IBM z Systems - Extended Life Cycle 9.8 s390x

Fixes

• BZ - 2369367 - CVE-2025-5351 libssh: Double Free Vulnerability in libssh Key Export Functions
• BZ - 2376184 - CVE-2025-4878 libssh: Use of uninitialized variable in privatekey_from_file()
• BZ - 2376193 - CVE-2025-4877 libssh: Write beyond bounds in binary to base64 conversion functions
• BZ - 2383220 - CVE-2025-8114 libssh: NULL Pointer Dereference in libssh KEX Session ID Calculation
• BZ - 2383888 - CVE-2025-8277 libssh: Memory Exhaustion via Repeated Key Exchange in libssh
• BZ - 2433121 - CVE-2026-0966 libssh: libssh: Denial of Service via zero-length input in ssh_get_hexa()
• BZ - 2436979 - CVE-2026-0964 libssh: Improper sanitation of paths received from SCP servers
• BZ - 2436980 - CVE-2026-0965 libssh: libssh: Denial of Service via improper configuration file handling
• BZ - 2436981 - CVE-2026-0967 libssh: libssh: Denial of Service via inefficient regular expression processing
• BZ - 2436982 - CVE-2026-0968 libssh: libssh: Denial of Service due to malformed SFTP message
• RHEL-150661 - Backport low/medium CVE fixes to RHEL 9

CVEs

• CVE-2025-4877
• CVE-2025-4878
• CVE-2025-5351
• CVE-2025-8114
• CVE-2025-8277
• CVE-2026-0964
• CVE-2026-0965
• CVE-2026-0966
• CVE-2026-0967
• CVE-2026-0968

References

• https://access.redhat.com/security/updates/classification/#moderate
• https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/9/html/9.8_release_notes/index