Your message dated Mon, 31 Aug 2026 19:51:54 +0100
with message-id <[email protected]>
and subject line Re: Bug#1143936: openssh: CVE-2026-55655
has caused the Debian Bug report #1143936,
regarding openssh: CVE-2026-55655
to be marked as done.
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1143936: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1143936
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--- Begin Message ---
Source: openssh
X-Debbugs-CC: [email protected]
Severity: important
Tags: security
Hi,
The following vulnerability was published for openssh.
CVE-2026-55655[0]:
| A flaw was found in OpenSSH. A local unprivileged attacker on a
| Linux client host can hijack client-side X11 forwarding connections.
| This is possible by pre-binding the preferred abstract X socket name
| when X11 forwarding is enabled and a local UNIX-domain X socket is
| used. A successful attack can compromise the confidentiality of
| forwarded X11 traffic, including sensitive window contents and
| input, and may allow some manipulation of the forwarded session.
https://bugzilla.redhat.com/show_bug.cgi?id=2462250 is the only
reference and Red Hat released an update, but it's unclear whether
this is an issue in upstream OpenSSH or one of their patches.
If you fix the vulnerability please also make sure to include the
CVE (Common Vulnerabilities & Exposures) id in your changelog entry.
For further information see:
[0] https://security-tracker.debian.org/tracker/CVE-2026-55655
https://www.cve.org/CVERecord?id=CVE-2026-55655
Please adjust the affected versions in the BTS as needed.
--- End Message ---
--- Begin Message ---
On Sat, Aug 08, 2026 at 06:29:27PM +0200, Moritz Mühlenhoff wrote:
Source: openssh
X-Debbugs-CC: [email protected]
Severity: important
Tags: security
Hi,
The following vulnerability was published for openssh.
CVE-2026-55655[0]:
| A flaw was found in OpenSSH. A local unprivileged attacker on a
| Linux client host can hijack client-side X11 forwarding connections.
| This is possible by pre-binding the preferred abstract X socket name
| when X11 forwarding is enabled and a local UNIX-domain X socket is
| used. A successful attack can compromise the confidentiality of
| forwarded X11 traffic, including sensitive window contents and
| input, and may allow some manipulation of the forwarded session.
https://bugzilla.redhat.com/show_bug.cgi?id=2462250 is the only
reference and Red Hat released an update, but it's unclear whether
this is an issue in upstream OpenSSH or one of their patches.
Red Hat fixed this in
https://src.fedoraproject.org/rpms/openssh/c/fdea50ab12e005f274ff8e4aa6f1210730e866f8?branch=rawhide.
I looked at this and it is fairly clearly an issue with one of their
patches (which they've since dropped, in
https://src.fedoraproject.org/rpms/openssh/c/f48279187d5eeefbfa05d6294afe753bb3d1c61d?branch=rawhide).
Debian has never had a similar patch, so we're unaffected.
Thanks,
--
Colin Watson (he/him) [[email protected]]
--- End Message ---
