CVE & CISA-KEV Catalog

CVE-2025-8277

LOW
3.1
CVSS v3
NVD

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.

How to fix

Remediation Available
libsshDebian
Fixed in:0.9.8-0+deb11u2CVE-2025-8277
Fixed in:0.10.6-0+deb12u2CVE-2025-8277
Fixed in:0.11.2-1+deb13u1CVE-2025-8277
Fixed in:0.11.3-1CVE-2025-8277
libsshRed Hat / RHEL
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
libsshRocky
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
libssh-configRocky
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
libssh-configRed Hat / RHEL
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
libssh-debuginfoRocky
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
libssh-debuginfoRed Hat / RHEL
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
libssh-debugsourceRocky
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
libssh-debugsourceRed Hat / RHEL
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
libssh-develRocky
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
libssh-develRed Hat / RHEL
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
Fixed in:0:0.10.4-18.el9RHSA-2026:18683
libsshUbuntu
Fixed in:0.6.3-4.3ubuntu0.6+esm4USN-8051-2
Fixed in:0.8.0~20170825.94fa1e38-1ubuntu0.7+esm6USN-8051-2
Fixed in:0.9.3-2ubuntu2.5+esm3USN-8051-2
Fixed in:0.9.6-2ubuntu0.22.04.6USN-8051-1
Fixed in:0.10.6-2ubuntu0.3USN-8051-1
Fixed in:0.11.2-1ubuntu0.2USN-8051-1
libssh-4Ubuntu
Fixed in:0.6.3-4.3ubuntu0.6+esm4USN-8051-2
Fixed in:0.8.0~20170825.94fa1e38-1ubuntu0.7+esm6USN-8051-2
Fixed in:0.9.3-2ubuntu2.5+esm3USN-8051-2
Fixed in:0.9.6-2ubuntu0.22.04.6USN-8051-1
Fixed in:0.10.6-2ubuntu0.3USN-8051-1
Fixed in:0.11.2-1ubuntu0.2USN-8051-1

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork
Attack ComplexityHigh
Privileges RequiredLow
User InteractionNone
ScopeUnchanged

Impact

ConfidentialityNone
IntegrityNone
AvailabilityLow

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L

Exploit Intelligence

0.38%probability of exploitation in 30 days
29thpercentile

Low risk: more likely to be exploited than 29% of all known CVEs.

References

Related Vulnerabilities

Other CWE-401 (Missing Release of Memory (Memory Leak)) vulnerabilities, ordered by exploit likelihood. View all

CVESeverityCVSSEPSSExploitedFix
CVE-2020-13934High7.564%-Fix
CVE-2016-6304High7.563%-Fix
CVE-2019-12265Medium5.355%-Fix
CVE-2001-0136Medium5.045%--
CVE-2016-4232High7.536%--
CVE-2001-0543Medium5.021%--
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-06-30.