CVE-2026-59849: libssh Infinite Loop
CVSS: 7.5v3.1HighAnalyzed
AliasesUBUNTU-CVE-2026-59849DEBIAN-CVE-2026-59849CGA-3mwc-9567-9w35CGA-5jp8-xwqq-vqghCGA-5v4v-27g3-878wCGA-659j-3q7w-h6mjCGA-jg44-mg79-p9prCGA-vwx7-6hwx-wfjx
Published 21-07-2026Last modified 19-08-2026
Vulnerability summary
CVE-2026-59849 is a high (CVSS 7.5) Infinite Loop vulnerability in libssh. EPSS estimates a 0.44% chance of exploitation in the next 30 days, higher than 36.6% of scored vulnerabilities.
CVSS score
7.5/10
010
High · v3.1 (NVD)EPSS score
0.44%
0%100%
Low · +0.19 pp in 30 daysKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded
Advisory lineage
Upstream 0 · Downstream 9 · Related 7Timeline
- 21-07-2026PublishedVulnerability first disclosed.
- 19-08-2026Last modifiedVulnerability information updated.
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.
CVSS metrics
4 scores · 4 sources · 1 versionHigh 7.5Preferred score · NVD (NIST)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HSources4 sources · 3.1–7.5
- CVE.orgCNA3.1LowCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:LDiffers
- OSV · UbuntuEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- OSV · DebianEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
0.44%
Chance of exploitation in the next 30 days
Percentile
37%
Versus all other CVEs
30-day change
+0.19 pp
From 0.24% on 18-09-2026
18-09-202618-10-2026
EPSS score0.44%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Redhat10 products
- enterprise_linux10.0 | 10.2
- enterprise_linux_for_els10.2
- enterprise_linux_for_eus10.2
- enterprise_linux_for_ibm_z_systems10.0 | 10.2
- enterprise_linux_for_ibm_z_systems_els10.2
Chainguard3 products
- libssh< 0.12.1-r0
- libssh-dev< 0.12.1-r0
- libssh2All versions (No fix recorded)
Wolfi3 products
- libssh< 0.12.1-r0
- libssh-dev< 0.12.1-r0
- libssh2All versions (No fix recorded)
Debian1 product
- libsshAll versions (No fix recorded) | < 0.11.5-0+deb13u1 | < 0.12.1-1
Libssh1 product
- libssh≥ 0.11.0, < 0.11.5 | 0.12.0
Ubuntu1 product
- libssh< 0.11.3-1ubuntu2.1
6 vendors · 19 products
