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CVE-2026-59849: A flaw was found in libssh

25
Routine
LOW 3.1WATCHLISTUPGRADEMITIGATEMITIGATE

CVE-2026-59849 is a low-severity flaw (CVSS 3.1) affecting libssh, hardened images, enterprise linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

  • On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score3.1 (Low)
Attack vectorNetwork (remote)
Attack complexityHigh
Privileges neededLow
User interactionNone
EPSS exploit chance0.4% (top 62%)
CISA exploited listNo
WeaknessCWE-835
Published2026-07-21
Last modified2026-09-22
Publisher (CNA): Red Hat, Inc. · Vendor: libssh · redhat

Share: LinkedIn · X · Reddit

Last updated 2026-09-22 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

libssh libssh UPGRADE
Affected: >= 0.11.0 and < 0.11.5 · 0.12.0
Fixed in: 0.11.5
Safe to downgrade to: a release before 0.11.0
1. Check installed version
apt-cache policy libssh || rpm -q libssh || libssh --version
2. UPGRADE to 0.11.5 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade libssh
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade libssh
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
3. If no update is available yet, DOWNGRADE to a release before 0.11.0 (Debian / Ubuntu)
apt-cache madison libssh sudo apt install libssh=<VERSION_BEFORE_0.11.0> sudo apt-mark hold libssh
3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list libssh sudo dnf downgrade libssh-<VERSION_BEFORE_0.11.0> sudo dnf versionlock add libssh
Downgrade risk
Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.
After downgrade
Restart the service, and keep the package held until a fixed release ships.
redhat hardened images MITIGATE
Affected: all versions
Fixed in: no fixed release known
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy hardened-images || rpm -q hardened-images || hardened-images --version
No fixed or unaffected release known
Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.
redhat enterprise linux MITIGATE
Affected: 10.0 · 10.2
Fixed in: no fixed release known
Safe to downgrade to: a release before 10.0
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
redhat enterprise linux for els MITIGATE
Affected: 10.2
Fixed in: no fixed release known
Safe to downgrade to: a release before 10.2
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
redhat enterprise linux for eus MITIGATE
Affected: 10.2
Fixed in: no fixed release known
Safe to downgrade to: a release before 10.2
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
redhat enterprise linux for ibm z systems MITIGATE
Affected: 10.0 · 10.2
Fixed in: no fixed release known
Safe to downgrade to: a release before 10.0
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-59849?

libssh: upgrade to 0.11.5; hardened images: mitigate or apply the listed mitigation; enterprise linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-59849 being exploited?

CVE-2026-59849 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-59849 affect?

CVE-2026-59849 affects libssh, hardened images, enterprise linux. Severity is low (CVSS 3.1). 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 o

How urgent is CVE-2026-59849?

Priority 25/100. On your watchlist

Related CVEs

References

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