CVE-2025-8277Libssh: memory exhaustion via repeated key exchange in libssh
- 3.1LowCVSS base score
- 0.43%Exploitation in 30 daysEPSS · top 62% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
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.
Timeline
ID reserved
By redhat
- 43 days later
· 43 days later
Published
- 14 months later
· 14 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| redhatCNA (assigner) | 3.1 | Low3.1 | CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L |
| NVDNVD · Deferred | 3.1 | Low3.1 | CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L |
- EPSS (exploitation in 30 days)
- 0.43% · top 62% of all CVEs (15 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Low 3.1.
Affected products
libssh
- affected 0.6.0 – < 0.11.3
Red Hat · Red Hat Enterprise Linux 9
- unaffected 0:0.10.4-18.el9 – < *
Red Hat · Red Hat Enterprise Linux 9
- unaffected 0:0.10.4-18.el9 – < *
Red Hat · Red Hat Enterprise Linux 10
All versions: affected
Red Hat · Red Hat Enterprise Linux 6
All versions: unknown
Red Hat · Red Hat Enterprise Linux 7
All versions: affected
Red Hat · Red Hat Enterprise Linux 8
All versions: affected
Red Hat · Red Hat OpenShift Container Platform 4
All versions: affected
Red Hat · Red Hat OpenShift Container Platform 4
All versions: affected
What to do
Workaround: Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability. It is strongly advised to apply updated libssh packages once available to prevent memory exhaustion risks on client systems.
References
References4
- RHSA-2026:18683 (opens in a new tab)vendor-advisoryx_refsource_REDHAT
- https://access.redhat.com/security/cve/CVE-2025-8277 (opens in a new tab)vdb-entryx_refsource_REDHAT
- RHBZ#2383888 (opens in a new tab)issue-trackingx_refsource_REDHAT
- https://www.libssh.org/security/advisories/CVE-2025-8277.txt (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2025-27246 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2025-8277)Record last updated .