Red Hat Product Errata RHSA-2026:55855 - Security Advisory Issued: 2026-08-17 Updated: 2026-08-17 RHSA-2026:55855 - Security Advisory Overview Updated Packages Synopsis Important: libssh security update Type/Severity Security Advisory: Important Red Hat Lightspeed patch analysis Identify and remediate systems affected by this advisory. View affected systems Topic An update for libssh is now available for Red Hat Enterprise Linux 10. 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 libssh is a library which implements the SSH protocol. It can be used to implement client and server applications. Security Fix(es): libssh: libssh: information disclosure via short GSSAPI Curve25519 public key (CVE-2026-59842) libssh: libssh: denial of service via zero advertised channel packet size (CVE-2026-59843) libssh: libssh: denial of service via oversized SFTP read length (CVE-2026-59844) libssh: libssh: denial of service via unchecked ProxyCommand fork() failure (CVE-2026-59845) libssh: libssh: information disclosure via ProxyCommand %r username expansion (CVE-2026-59846) libssh: libssh: integrity downgrade via OpenSSL AES-GCM tag verification (CVE-2026-59847) libssh: libssh: denial of service via SFTP responses with unknown request IDs (CVE-2026-59848) libssh: libssh: denial of service via automatic certificate authentication loop (CVE-2026-59849) libssh: libssh: use-after-free via data callbacks on closed channels (CVE-2026-59850) libssh: libssh: authentication bypass via missing GSSAPI principal check (CVE-2026-59851) libssh: libssh: stack buffer overflow in SFTP server longname construction (CVE-2026-15370) 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 10 x86_64 Red Hat Enterprise Linux for x86_64 - Extended Update Support 10.2 x86_64 Red Hat Enterprise Linux for IBM z Systems 10 s390x Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 10.2 s390x Red Hat Enterprise Linux for Power, little endian 10 ppc64le Red Hat Enterprise Linux for Power, little endian - Extended Update Support 10.2 ppc64le Red Hat Enterprise Linux for ARM 64 10 aarch64 Red Hat Enterprise Linux for ARM 64 - Extended Update Support 10.2 aarch64 Red Hat Enterprise Linux for ARM 64 - 4 years of updates 10.2 aarch64 Red Hat Enterprise Linux for IBM z Systems - 4 years of updates 10.2 s390x Red Hat Enterprise Linux for Power, little endian - 4 years of support 10.2 ppc64le Red Hat Enterprise Linux for x86_64 - 4 years of updates 10.2 x86_64 Red Hat Enterprise Linux for x86_64 - Extended Life Cycle 10.2 x86_64 Red Hat Enterprise Linux for ARM 64 - Extended Life Cycle 10.2 aarch64 Red Hat Enterprise Linux for Power, little endian - Extended Life Cycle 10.2 ppc64le Red Hat Enterprise Linux for IBM z Systems - Extended Life Cycle 10.2 s390x Fixes BZ - 2498168 - CVE-2026-59842 libssh: libssh: information disclosure via short GSSAPI Curve25519 public key BZ - 2498176 - CVE-2026-59843 libssh: libssh: denial of service via zero advertised channel packet size BZ - 2498177 - CVE-2026-59844 libssh: libssh: denial of service via oversized SFTP read length BZ - 2498178 - CVE-2026-59845 libssh: libssh: denial of service via unchecked ProxyCommand fork() failure BZ - 2498179 - CVE-2026-59846 libssh: libssh: information disclosure via ProxyCommand %r username expansion BZ - 2498180 - CVE-2026-59847 libssh: libssh: integrity downgrade via OpenSSL AES-GCM tag verification BZ - 2498181 - CVE-2026-59848 libssh: libssh: denial of service via SFTP responses with unknown request IDs BZ - 2498182 - CVE-2026-59849 libssh: libssh: denial of service via automatic certificate authentication loop BZ - 2498183 - CVE-2026-59850 libssh: libssh: use-after-free via data callbacks on closed channels BZ - 2498184 - CVE-2026-59851 libssh: libssh: authentication bypass via missing GSSAPI principal check BZ - 2499049 - CVE-2026-15370 libssh: libssh: stack buffer overflow in SFTP server longname construction CVEs CVE-2026-15370 CVE-2026-59842 CVE-2026-59843 CVE-2026-59844 CVE-2026-59845 CVE-2026-59846 CVE-2026-59847 CVE-2026-59848 CVE-2026-59849 CVE-2026-59850 CVE-2026-59851 References https://access.redhat.com/security/updates/classification/#important Note: More recent versions of these packages may be available. Click a package name for more details. Red Hat Enterprise Linux for x86_64 10 SRPM libssh-0.12.0-3.el10_2.src.rpm SHA-256: abfd866c62f7a3cc718b01c1f2c534644314f020553456fef2d01e3e74af6e30 x86_64 libssh-0.12.0-3.el10_2.x86_64.rpm SHA-256: e510adfbe957332cd1baf895238c6c179f6ce1460b92bb022d52772a11ba5cee libssh-config-0.12.0-3.el10_2.noarch.rpm SHA-256: 0bed78001fd745ddac7a1efb8e46dae4df4379039530c3aab87bda051f43974d libssh-debuginfo-0.12.0-3.el10_2.x86_64.rpm SHA-256: 5f45d9872e668afd62c61627aa75e1d385428587bfe1517a78983e39983d2c2f libssh-debuginfo-0.12.0-3.el10_2.x86_64.rpm SHA-256: 5f45d9872e668afd62c61627aa75e1d385428587bfe1517a78983e39983d2c2f libssh-debugsource-0.12.0-3.el10_2.x86_64.rpm SHA-256: 457cf5168e53af7cf21577d0d00dd5d1e03f53f09a86823453a5735e5bace29d libssh-debugsource-0.12.0-3.el10_2.x86_64.rpm SHA-256: 457cf5168e53af7cf21577d0d00dd5d1e03f53f09a86823453a5735e5bace29d libssh-devel-0.12.0-3.el10_2.x86_64.rpm SHA-256: e591354c5c9dd4ce480d764f2ebff0fd4385c68a1fe93e6cf5d936546004f51d Red Hat Enterprise Linux for x86_64 - Extended Update Support 10.2 SRPM libssh-0.12.0-3.el10_2.src.rpm SHA-256: abfd866c62f7a3cc718b01c1f2c534644314f020553456fef2d01e3e74af6e30 x86_64 libssh-0.12.0-3.el10_2.x86_64.rpm SHA-256: e510adfbe957332cd1baf895238c6c179f6ce1460b92bb022d52772a11ba5cee libssh-config-0.12.0-3.el10_2.noarch.rpm SHA-256: 0bed78001fd745ddac7a1efb8e46dae4df4379039530c3aab87bda051f43974d libssh-debuginfo-0.12.0-3.el10_2.x86_64.rpm SHA-256: 5f45d9872e668afd62c61627aa75e1d385428587bfe1517a78983e39983d2c2f libssh-debuginfo-0.12.0-3.el10_2.x86_64.rpm SHA-256: 5f45d9872e668afd62c61627aa75e1d385428587bfe1517a78983e39983d2c2f libssh-debugsource-0.12.0-3.el10_2.x86_64.rpm SHA-256: 457cf5168e53af7cf21577d0d00dd5d1e03f53f09a86823453a5735e5bace29d libssh-debugsource-0.12.0-3.el10_2.x86_64.rpm SHA-256: 457cf5168e53af7cf21577d0d00dd5d1e03f53f09a86823453a5735e5bace29d libssh-devel-0.12.0-3.el10_2.x86_64.rpm SHA-256: e591354c5c9dd4ce480d764f2ebff0fd4385c68a1fe93e6cf5d936546004f51d Red Hat Enterprise Linux for IBM z Systems 10 SRPM libssh-0.12.0-3.el10_2.src.rpm SHA-256: abfd866c62f7a3cc718b01c1f2c534644314f020553456fef2d01e3e74af6e30 s390x libssh-0.12.0-3.el10_2.s390x.rpm SHA-256: dd879922c172eea7bc067ceea05013314f7fc88d832aa14b584d8b02d82e97a3 libssh-config-0.12.0-3.el10_2.noarch.rpm SHA-256: 0bed78001fd745ddac7a1efb8e46dae4df4379039530c3aab87bda051f43974d libssh-debuginfo-0.12.0-3.el10_2.s390x.rpm SHA-256: 63d41c65b609afc1fb71122efd57cafd8e10962b890a100f7b253a173a6672f1 libssh-debuginfo-0.12.0-3.el10_2.s390x.rpm SHA-256: 63d41c65b609afc1fb71122efd57cafd8e10962b890a100f7b253a173a6672f1 libssh-debugsource-0.12.0-3.el10_2.s390x.rpm SHA-256: 7e09eafe5fe50bf9fe0265fd490ca0e7eb4d8d63cf2cbed53161f79decb2dfe6 libssh-debugsource-0.12.0-3.el10_2.s390x.rpm SHA-256: 7e09eafe5fe50bf9fe0265fd490ca0e7eb4d8d63cf2cbed53161f79decb2dfe6 libssh-devel-0.12.0-3.el10_2.s390x.rpm SHA-256: abc0a847edf9c6ee07faf1e3a1ec0879738a95772ab313e8074c695d5e78b95a Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 10.2 SRPM libssh-0.12.0-3.el10_2.src.rpm SHA-256: abfd866c62f7a3cc718b01c1f2c534644314f020553456fef2d01e3e74af6e30 s390x libssh-0.12.0-3.el10_2.s390x.rpm SHA-256: dd879922c172eea7bc067ceea05013314f7fc88d832aa14b584d8b02d82e97a3 libssh-config-0.12.0-3.el10_2.noarch.rpm SHA-256: 0bed78001fd745ddac7a1efb8e46dae4df4379039530c3aab87bda051f43974d libssh-debuginfo-0.12.0-3.el10_2.s390x.rpm SHA-256: 63d41c65b609afc1fb71122efd57cafd8e10962b890a100f7b253a173a6672f1 libssh-debuginfo-0.12.0-3.el10_2.s390x.rpm SHA-256: 63d41c65b609afc1fb71122efd57cafd8e10962b890a100f7b253a173a6672f1 libssh-debugsource-0.12.0-3.el10_2.s390x.rpm SHA-256: 7e09eafe5fe50bf9fe0265fd490ca0e7eb4d8d63cf2cbed53161f79decb2dfe6 libssh-debugsource-0.12.0-3.el10_2.s390x.rpm SHA-256: 7e09eafe5fe50bf9fe0265fd490ca0e7eb4d8d63cf2cbed53161f79decb2dfe6 libssh-devel-0.12.0-3.el10_2.s390x.rpm SHA-256: abc0a847edf9c6ee07faf1e3a1ec0879738a95772ab313e8074c695d5e78b95a Red Hat Enterprise Linux for Power, little endian 10 SRPM libssh-0.12.0-3.el10_2.src.rpm SHA-256: abfd866c62f7a3cc718b01c1f2c534644314f020553456fef2d01e3e74af6e30 ppc64le libssh-0.12.0-3.el10_2.ppc64le.rpm SHA-256: bbbc564eaadbde32b467a5361387f2dd9685f07a4257a8bc395f494a7098333a libssh-config-0.12.0-3.el10_2.noarch.rpm SHA-256: 0bed78001fd745ddac7a1efb8e46dae4df4379039530c3aab87bda051f43974d libssh-debuginfo-0.12.0-3.el10_2.ppc64le.rpm SHA-256: d988d03e79c25a0fe4bf40a0e21ea9b3a08e875292a3aafec5bc948f04e5a76a libssh-debuginfo-0.12.0-3.el10_2.ppc64le.rpm SHA-256: d988d03e79c25a0fe4bf40a0e21ea9b3a08e875292a3aafec5bc948f04e5a76a libssh-debugsource-0.12.0-3.el10_2.ppc64le.rpm SHA-256: d37954718f0c99019c4b5b07e0c9d49c97ad121a360a3558f841be9a1906ca4c libssh-debugsource-0.12.0-3.el10_2.ppc64le.rpm SHA-256: d37954718f0c99019c4b5b07e0c9d49c97ad121a360a3558f841be9a1906ca4c libssh-devel-0.12.0-3.el10_2.ppc64le.rpm SHA-256: 6c5d5a394c07ca562a5bb3086e438f2d3c9fa83f1ae65b58270f9c4ba9c721eb Red Hat Enterprise Linux for Power, little endian - Extended Update Support 10.2 SRPM libssh-0.12.0-3.el10_2.src.rpm SHA-256: abfd866c62f7a3cc718b01c1f2c534644314f020553456fef2d01e3e74af6e30 ppc64le libssh-0.12.0-3.el10_2.ppc6