Openssh: openssh: shared lz77 compression dictionary leaks plaintext across channels

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-110926
StatePUBLISHED
Assignerredhat
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-15 06:17:01 UTC
Updated2026-10-15 20:17:09 UTC
DescriptionA flaw was found in OpenSSH. When compression is negotiated, channels on the same connection share one LZ77 dictionary. A peer who can write on one channel can recover plaintext from another channel by chosen-plaintext lengths.

Risk And Classification

Primary CVSS: v3.1 5.3 MEDIUM from [email protected]

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

EPSS: 0.002530000 probability, percentile 0.155950000 (date 2026-10-15)

Problem Types: CWE-203 | CWE-203 Observable Discrepancy

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.3MEDIUMCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
3.1CNACVSS5.3MEDIUMCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Red Hat Red Hat Hardened Images unaffected 10.5p1-1.2.hum1 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 10 Not specified Not specified
CNA Red Hat Red Hat Enterprise Linux 6 Not specified Not specified
CNA Red Hat Red Hat Enterprise Linux 7 Not specified Not specified
CNA Red Hat Red Hat Enterprise Linux 8 Not specified Not specified
CNA Red Hat Red Hat Enterprise Linux 9 Not specified Not specified
CNA Red Hat Red Hat Hardened Images Not specified Not specified
CNA Red Hat Red Hat OpenShift Container Platform 4 Not specified Not specified
CNA Red Hat Red Hat OpenShift Container Platform 4 Not specified Not specified

References

ReferenceSourceLinkTags
access.redhat.com/errata/RHSA-2026:82247 [email protected] access.redhat.com
bugzilla.redhat.com/show_bug.cgi [email protected] bugzilla.redhat.com
access.redhat.com/security/cve/CVE-2026-110926 [email protected] access.redhat.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Red Hat would like to thank Fabian Bäumer and Marcus Brinkmann for reporting this issue. (en)

Additional Advisory Data

SourceTimeEvent
CNA2026-10-15T04:17:08.197ZReported to Red Hat.
CNA2026-10-15T00:00:00.000ZMade public.

Workarounds

CNA: Leave Compression disabled. The client default is already off. Prefer application-level compression instead of SSH compression.

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