CVE-2026-3497: Vulnerability in the OpenSSH GSSAPI delta included in various Linux distributions

This month

HIGH 7.5REMOTEWATCHLISTDOWNGRADEMITIGATEMITIGATE

CVE-2026-3497 is a high-severity flaw (CVSS 7.5) affecting ubuntu linux, openssh, ubuntu linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Vulnerability in the OpenSSH GSSAPI delta included in various Linux distributions. This vulnerability affects the GSSAPI patches added by various Linux distributions and does not affect the OpenSSH upstream project itself. The usage of sshpkt_disconnect() on an error, which does not terminate the process, allows an attacker to send an unexpected GSSAPI message type during the GSSAPI key exchange to the server, which will call the underlying funct

Why this priority

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

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	2.3% (top 17%)
CISA exploited list	No
Weakness	CWE-908, CWE-824
Published	2026-03-12
Last modified	2026-10-15

Publisher (CNA): Canonical Ltd. · Vendor: canonical · debian · openbsd · redhat

Last updated 2026-10-15 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-03-12 19:16 UTCPublished CVE record published
2026-10-15 02:19 UTCUpdated Record last modified

canonical ubuntu linux DOWNGRADE

Affected: 25.10

Fixed in: no fixed release known

Safe to downgrade to: a release before 25.10

1. Check installed version

apt-cache policy ubuntu-linux || rpm -q ubuntu-linux || ubuntu-linux --version

2. No fixed release: DOWNGRADE to a release before 25.10 (Debian / Ubuntu)

apt-cache madison ubuntu-linux sudo apt install ubuntu-linux=<VERSION_BEFORE_25.10> sudo apt-mark hold ubuntu-linux

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list ubuntu-linux sudo dnf downgrade ubuntu-linux-<VERSION_BEFORE_25.10> sudo dnf versionlock add ubuntu-linux

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.

openbsd openssh 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 openssh || rpm -q openssh || openssh --version

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

canonical ubuntu linux MITIGATE

Affected: 20.04 · 22.04 · 24.04

Fixed in: no fixed release known

Safe to downgrade to: a release before 20.04

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.

debian debian linux MITIGATE

Affected: 11.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 11.0

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 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.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.

Fedora ELN · fonttools · FIXED · 4.68.0-1.eln159 · FEDORA-2026-37fa4b964c · source

sudo dnf upgrade --advisory=FEDORA-2026-37fa4b964c

Fedora 46 · fonttools · FIXED · 4.68.0-1.fc46 · FEDORA-2026-65d6c01c75 · source

sudo dnf upgrade --advisory=FEDORA-2026-65d6c01c75

Ubuntu 20.04 · openssh · FIXED · 1:8.2p1-4ubuntu0.13+esm1

sudo apt update && sudo apt install --only-upgrade openssh dpkg --compare-versions "$(dpkg-query -W -f='${Version}' openssh)" ge "1:8.2p1-4ubuntu0.13+esm1" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 22.04 · openssh · FIXED · 1:8.9p1-3ubuntu0.14

sudo apt update && sudo apt install --only-upgrade openssh dpkg --compare-versions "$(dpkg-query -W -f='${Version}' openssh)" ge "1:8.9p1-3ubuntu0.14" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 24.04 · openssh · FIXED · 1:9.6p1-3ubuntu13.15

sudo apt update && sudo apt install --only-upgrade openssh dpkg --compare-versions "$(dpkg-query -W -f='${Version}' openssh)" ge "1:9.6p1-3ubuntu13.15" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 25.10 · openssh · FIXED · 1:10.0p1-5ubuntu5.1

sudo apt update && sudo apt install --only-upgrade openssh dpkg --compare-versions "$(dpkg-query -W -f='${Version}' openssh)" ge "1:10.0p1-5ubuntu5.1" && echo PATCHED || echo STILL-VULNERABLE

Debian 12 · openssh · FIXED · 1:9.2p1-2+deb12u9

sudo apt update && sudo apt install --only-upgrade openssh dpkg --compare-versions "$(dpkg-query -W -f='${Version}' openssh)" ge "1:9.2p1-2+deb12u9" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · openssh · FIXED · 1:10.0p1-7+deb13u2

sudo apt update && sudo apt install --only-upgrade openssh dpkg --compare-versions "$(dpkg-query -W -f='${Version}' openssh)" ge "1:10.0p1-7+deb13u2" && echo PATCHED || echo STILL-VULNERABLE

RHEL 10 · openssh · FIXED · openssh-9.9p1-13.el10_1

sudo dnf upgrade --advisory=RHSA-2026:6463 rpm -q openssh

RHEL 10.0 Extended Update Support · openssh · FIXED · openssh-9.9p1-7.el10_0.2

sudo dnf upgrade --advisory=RHSA-2026:7107 rpm -q openssh

RHEL 8 · openssh · FIXED · openssh-8.0p1-28.el8_10

sudo dnf upgrade --advisory=RHSA-2026:6461 rpm -q openssh

RHEL 8.4 Advanced Mission Critical Update Support · openssh · FIXED · openssh-8.0p1-7.el8_4.1

sudo dnf upgrade --advisory=RHSA-2026:15891 rpm -q openssh

RHEL 8.4 Extended Update Support Long-Life Add-On · openssh · FIXED · openssh-8.0p1-7.el8_4.1

sudo dnf upgrade --advisory=RHSA-2026:15891 rpm -q openssh

Amazon Linux 2023 · see advisory · FIXED · ALAS2023-2026-1745 · source

sudo dnf update --advisory=ALAS2023-2026-1745

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Write-up: cert-portal.siemens.com/productcert/html/ssa-019113.html
Write-up: cert-portal.siemens.com/productcert/html/ssa-457936.html

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-2026-3497?

ubuntu linux: downgrade or apply the listed mitigation; openssh: mitigate or apply the listed mitigation; ubuntu linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-3497 being exploited?

CVE-2026-3497 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-2026-3497 affect?

CVE-2026-3497 affects ubuntu linux, openssh, ubuntu linux. Severity is high (CVSS 7.5). Vulnerability in the OpenSSH GSSAPI delta included in various Linux distributions. This vulnerability affects the GSSAPI patches added by various Linux distributions and does not affect the OpenSSH upstream project itself. The usage of sshp

How urgent is CVE-2026-3497?

Priority 57/100. High severity; Remotely exploitable, no login, no user action; On your watchlist

Software pages

OpenSSH vulnerabilities · Ubuntu vulnerabilities · Debian vulnerabilities

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References

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