| Package | openssh |
|---|---|
| Version | 1:7.9p1-10+deb10u7 (buster) |
| Related CVEs | CVE-2025-61984 CVE-2025-61985 CVE-2026-3497 CVE-2026-35385 CVE-2026-35386 CVE-2026-35387 CVE-2026-35388 CVE-2026-35414 |
Several vulnerabilities have been discovered in OpenSSH, an implementation of the SSH protocol suite.
CVE-2025-61984
ssh allows control characters in usernames that originate from certain
possibly untrusted sources, potentially leading to code execution when a
ProxyCommand is used.
CVE-2025-61985
ssh allows the '\0' character in an ssh:// URI, potentially leading to code
execution when a ProxyCommand is used.
CVE-2026-3497
Jeremy Brown discovered a flaw in the GSSAPI Key Exchange patch applied
in Debian to OpenSSH, an implementation of the SSH protocol suite,
affecting non-default configurations with the GSSAPIKeyExchange setting
enabled. A remote attacker can take advantage of this flaw to cause a
denial of service, or potentially the execution of arbitrary code.
This update properly initialize some GSS-API variables out of caution,
although most of this vulnerability does not apply to this version.
CVE-2026-35385
When downloading files as root in legacy (-O) mode and without the -p
(preserve modes) flag set, scp did not clear setuid/setgid bits from
downloaded files as one might typically expect. This bug dates back to the
original Berkeley rcp program. Reported by Christos Papakonstantinou of
Cantina and Spearbit.
CVE-2026-35386
Validation of shell metacharacters in user names supplied on the
command-line was performed too late to prevent some situations where they
could be expanded from %-tokens in ssh_config. For certain configurations,
such as those that use a "%u" token in a "Match exec" block, an attacker
who can control the user name passed to ssh(1) could potentially execute
arbitrary shell commands. Reported by Florian Kohnhäuser.
OpenSSH developers continue to recommend against directly exposing ssh(1)
and other tools' command-lines to untrusted input. Mitigations as the one
addressing this issue can not be absolute given the variety of shells and
user configurations in use.
CVE-2026-35387
ssh can use unintended ECDSA algorithms. Listing of any ECDSA algorithm in
PubkeyAcceptedAlgorithms or HostbasedAcceptedAlgorithms is misinterpreted
to mean all ECDSA algorithms. Reported by Christos Papakonstantinou of
Cantina and Spearbit.
CVE-2026-35388
Connection multiplexing confirmation (requested using "ControlMaster
ask/autoask") was not being tested for proxy mode multiplexing sessions (i.e.
"ssh -O proxy ..."). Reported by Michalis Vasileiadis.
CVE-2026-35414
When matching an authorized_keys principals="" option against a list of
principals in a certificate, an incorrect algorithm was used that could
allow inappropriate matching in cases where a principal name in the
certificate contains a comma character. Exploitation of the condition requires
an authorized_keys principals="" option that lists more than one principal
*and* a CA that will issue a certificate that encodes more than one of
these principal names separated by a comma (typical CAs strongly constrain
which principal names they will place in a certificate). This condition
only applies to user- trusted CA keys in authorized_keys, the main
certificate authentication path
(TrustedUserCAKeys/AuthorizedPrincipalsFile) is not affected. Reported by
Vladimir Tokarev.
For Debian 10 buster, these problems have been fixed in version 1:7.9p1-10+deb10u7.
We recommend that you upgrade your openssh packages.
Further information about Extended LTS security advisories can be found in the dedicated section of our website.