Vulnerability · Published Jul 21, 2026 · Assigned by redhat
CVE-2026-59849Libssh: libssh: denial of service via automatic certificate authentication loop
Low 3.1
In plain English
A low-severity infinite loop in Red Hat Enterprise Linux 10 from Red Hat. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 38% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)3.1Low
Exploit odds (30 days)0.4%top 61.7% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
A flaw was found in libssh. Logic errors in automatic certificate-based public key authentication can cause libssh clients to loop indefinitely when configured certificates are missing or repeatedly rejected by a server, leading to denial of service.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:10 | libssh | 0.12.0-3.el10_2 | ALSA-2026:55855 |
| AlmaLinux:10 | libssh-config | 0.12.0-3.el10_2 | ALSA-2026:55855 |
| AlmaLinux:10 | libssh-devel | 0.12.0-3.el10_2 | ALSA-2026:55855 |
| Alpine:v3.24 | libssh | 0.12.1-r0 | ALPINE-CVE-2026-59849 |
| Debian:13 | libssh | 0.11.5-0+deb13u1 | DEBIAN-CVE-2026-59849 |
| Debian:14 | libssh | 0.12.1-1 | DEBIAN-CVE-2026-59849 |
| Rocky Linux:10 | libssh | 0:0.12.0-3.el10_2 | RLSA-2026:55855 |
| Ubuntu:22.04:LTS | libssh | 0.9.6-2ubuntu0.22.04.8 | USN-8699-1 |
| Ubuntu:24.04:LTS | libssh | 0.10.6-2ubuntu0.5 | USN-8699-1 |
| Ubuntu:26.04:LTS | libssh | 0.11.3-1ubuntu2.1 | USN-8699-1 |
| Ubuntu:26.04:LTS | libssh | 0.11.3-1ubuntu2.1 | UBUNTU-CVE-2026-59849 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Red Hat | Red Hat Enterprise Linux 10 | see references |
| Red Hat | Red Hat Hardened Images | see references |
| Red Hat | Red Hat Enterprise Linux 8 | see references |
| Red Hat | Red Hat Enterprise Linux 9 | see references |
Weakness: CWE-835 · Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L
References
- RHSA-2026:42922 vendor-advisory, x_refsource_REDHAT
- RHSA-2026:55855 vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/security/cve/CVE-2026-59849 vdb-entry, x_refsource_REDHAT
- RHBZ#2498182 issue-tracking, x_refsource_REDHAT