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Ubuntu LinuxApplication · Canonical

CVE-2026-3497

HIGH · 7.5 CVSS v3.1 Published 2026-03-12
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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 function and continue the execution of the program without setting the related connection variables. As the variables are not initialized to NULL the code later accesses those uninitialized variables, accessing random memory, which could lead to undefined behavior. The recommended workaround is to use ssh_packet_disconnect() instead, which does terminate the process. The impact of the vulnerability depends heavily on the compiler flag hardening configuration.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Vulnerability in the GSSAPI key exchange of OpenSSH as distributed in certain Linux distributions. The issue stems from using sshpkt_disconnect() (non-terminating) instead of ssh_packet_disconnect() (terminating) in error handling. An attacker can send an unexpected GSSAPI message type during key exchange, causing the code to continue without initializing connection variables, leading to undefined behavior from accessing uninitialized variables.

MitigationReplace sshpkt_disconnect() with ssh_packet_disconnect() in GSSAPI error handling paths, or disable GSSAPI key exchange if not required. Ensure compiler hardening flags are enabled to mitigate potential exploitation.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Ubuntu LinuxApplication
Affected:= 25.10= 20.04= 22.04= 24.04
Debian LinuxOperating system
Affected:= 11.0
Enterprise LinuxOperating system
Affected:= 8.0= 9.0= 10.0
OpensshApplication
Affected:all versions

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify OpenSSH version
    Run `sshd -v` or check package version with `dpkg -l openssh-server` (Debian/Ubuntu) or `rpm -q openssh-server` (RHEL)
    Affected if Installed version matches Ubuntu 20.04, 22.04, 24.04, 25.10; Debian 11.0; RHEL 8.0, 9.0, 10.0; or OpenBSD with OpenSSH all versions
  2. Determine if GSSAPI authentication is enabled
    Check sshd_config for 'GSSAPIAuthentication yes' or review /etc/ssh/sshd_config
    Affected if GSSAPIAuthentication is set to yes, enabling the vulnerable code path
  3. Check if GSSAPI key exchange is in use
    Review sshd logs and client/server configuration for GSSAPI-based key exchange connections
    Affected if GSSAPI key exchange is actively used, triggering the flawed code path
  4. Verify OpenSSH source code patch status
    If accessible, inspect source code in gss-serv.c or related GSSAPI modules for sshpkt_disconnect vs ssh_packet_disconnect usage
    Affected if Code still contains the vulnerable sshpkt_disconnect call in GSSAPI key exchange handling

A system is affected if it runs a vulnerable OpenSSH version from the affected ranges AND has GSSAPI authentication or key exchange enabled, allowing the flawed code path to be triggered.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Replace sshpkt_disconnect() with ssh_packet_disconnect() in GSSAPI error handling paths, or disable GSSAPI key exchange if not required. Ensure compiler hardening flags are enabled to mitigate potential exploitation.

Fix this in Ubuntu Linux Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,490
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-3497 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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