CVE-2026-59847: A flaw was found in libssh

Routine

MEDIUM 5.9REMOTEWATCHLISTUPGRADEMITIGATEMITIGATE

CVE-2026-59847 is a medium-severity flaw (CVSS 5.9) 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. Incorrect AES-GCM finalization checks in builds using the OpenSSL backend can effectively remove integrity protection, allowing an in-path attacker to modify plaintext on the wire without detection.

Why this priority

Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	5.9 (Medium)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.3% (top 74%)
CISA exploited list	No
Weakness	CWE-253, CWE-1310
Published	2026-07-21
Last modified	2026-09-04

Publisher (CNA): Red Hat, Inc. · Vendor: libssh · redhat

Last updated 2026-09-04 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-21 14:16 UTCPublished CVE record published
2026-09-04 19:23 UTCUpdated Record last modified

libssh libssh UPGRADE

Affected: >= 0.9.0 and < 0.11.5 · 0.12.0

Fixed in: 0.11.5

Safe to downgrade to: a release before 0.9.0

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 0.9.0 (Debian / Ubuntu)

apt-cache madison libssh sudo apt install libssh=<VERSION_BEFORE_0.9.0> 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_0.9.0> 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: 8.0 · 9.0 · 10.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 8.0

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-2026-59847?

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-2026-59847 being exploited?

CVE-2026-59847 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-2026-59847 affect?

CVE-2026-59847 affects libssh, hardened images, enterprise linux. Severity is medium (CVSS 5.9). A flaw was found in libssh. Incorrect AES-GCM finalization checks in builds using the OpenSSL backend can effectively remove integrity protection, allowing an in-path attacker to modify plaintext on the wire without detection.

How urgent is CVE-2026-59847?

Priority 37/100. Remotely exploitable, no login, no user action; On your watchlist

Software pages

OpenSSL vulnerabilities

Related CVEs

CVE-2026-59849 LOW 3.1 UPGRADE MITIGATE A flaw was found in libssh
CVE-2026-59842 LOW 3.7 DOWNGRADE MITIGATE A flaw was found in libssh
CVE-2026-15370 MEDIUM 6.7 UPGRADE MITIGATE A flaw was found in libssh
CVE-2026-59850 MEDIUM 4.3 MITIGATE MITIGATE A flaw was found in libssh
CVE-2026-59848 MEDIUM 5.3 MITIGATE MITIGATE A flaw was found in libssh

References

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