What’s Vulnerable › Vulnerabilities

CVE-2025-8277: Libssh: memory exhaustion via repeated key exchange in libssh

• Severity: low (CVSS 3.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-09-09 · updated 2026-10-18
• Weakness: CWE-401

Description

A flaw was found in libssh's handling of key exchange (KEX) processes when a client repeatedly sends incorrect KEX guesses. The library fails to free memory during these rekey operations, which can gradually exhaust system memory. This issue can lead to crashes on the client side, particularly when using libgcrypt, which impacts application stability and availability.

Affected products

• Red Hat OpenShift Container Platform 4.18: all versions
• Red Hat Enterprise Linux 10: all versions
• Red Hat Enterprise Linux 7: all versions
• Red Hat Enterprise Linux 8: all versions
• Red Hat Enterprise Linux 9: all versions — fixed in 0:0.10.4-18.el9

How to fix

Upgrade to a fixed version: Red Hat Enterprise Linux 9 0:0.10.4-18.el9. Check the vendor advisory for mitigations.

References

• https://access.redhat.com/errata/RHSA-2026:18683
• https://access.redhat.com/security/cve/CVE-2025-8277
• https://bugzilla.redhat.com/show_bug.cgi?id=2383888
• https://www.libssh.org/security/advisories/CVE-2025-8277.txt

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