OpenSSH shared compression dictionary leaks plaintext across channels
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- High
- Impact type
- Information disclosure
- Confidentiality · integrity · availability
- High · None · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-203.
Summary
When compression is negotiated, all channels on the same OpenSSH connection share one LZ77 compression dictionary. This flaw, tracked as CWE-203 Observable Discrepancy, lets a peer that can write on one channel recover plaintext from another channel on that connection.
Written with Claude Haiku 5.5 from the sources below · 2026-11-04
Description from the CNA
A 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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Red Hat | Red Hat Hardened Images | — | 10.5p1-1.2.hum1 | Patch available | CNA |
| Red Hat | Red Hat Enterprise Linux 10 | — | — | Not affected | CNA |
| Red Hat | Red Hat Enterprise Linux 6 | — | — | Not affected | CNA |
| Red Hat | Red Hat Enterprise Linux 7 | — | — | Not affected | CNA |
| Red Hat | Red Hat Enterprise Linux 8 | — | — | Not affected | CNA |
| Red Hat | Red Hat Enterprise Linux 9 | — | — | Not affected | CNA |
| Red Hat | Red Hat Hardened Images | — | — | Not affected | CNA |
| Red Hat | Red Hat OpenShift Container Platform 4 | — | — | Not affected | CNA |
| Red Hat | Red Hat OpenShift Container Platform 4 | — | — | Not affected | CNA |
- Red Hat Hardened Images VendorRed Hat Affected — Fixed in 10.5p1-1.2.hum1 Patch available CNA
- Red Hat Enterprise Linux 10 VendorRed Hat Affected — Fixed in — Not affected CNA
- Red Hat Enterprise Linux 6 VendorRed Hat Affected — Fixed in — Not affected CNA
- Red Hat Enterprise Linux 7 VendorRed Hat Affected — Fixed in — Not affected CNA
- Red Hat Enterprise Linux 8 VendorRed Hat Affected — Fixed in — Not affected CNA
- Red Hat Enterprise Linux 9 VendorRed Hat Affected — Fixed in — Not affected CNA
- Red Hat Hardened Images VendorRed Hat Affected — Fixed in — Not affected CNA
- Red Hat OpenShift Container Platform 4 VendorRed Hat Affected — Fixed in — Not affected CNA
- Red Hat OpenShift Container Platform 4 VendorRed Hat Affected — Fixed in — Not affected CNA
CPE names CNA · 7
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:/a:redhat:hummingbird:1 | 1 | — | Red Hat |
| cpe:/o:redhat:enterprise_linux:10 | 10 | — | Red Hat |
| cpe:/o:redhat:enterprise_linux:6 | 6 | — | Red Hat |
| cpe:/o:redhat:enterprise_linux:7 | 7 | — | Red Hat |
| cpe:/o:redhat:enterprise_linux:8 | 8 | — | Red Hat |
| cpe:/o:redhat:enterprise_linux:9 | 9 | — | Red Hat |
| cpe:/a:redhat:openshift:4 | 4 | — | Red Hat |
- cpe:/a:redhat:hummingbird:1 Versions 1 — ·Red Hat
- cpe:/o:redhat:enterprise_linux:10 Versions 10 — ·Red Hat
- cpe:/o:redhat:enterprise_linux:6 Versions 6 — ·Red Hat
- cpe:/o:redhat:enterprise_linux:7 Versions 7 — ·Red Hat
- cpe:/o:redhat:enterprise_linux:8 Versions 8 — ·Red Hat
- cpe:/o:redhat:enterprise_linux:9 Versions 9 — ·Red Hat
- cpe:/a:redhat:openshift:4 Versions 4 — ·Red Hat
Remediation
Red Hat Hardened Images is fixed in 10.5p1-1.2.hum1, delivered by RHSA-2026:82247. The sources list Red Hat Enterprise Linux 6, 7, 8, 9 and 10 and Red Hat OpenShift Container Platform 4 as not affected.
Written with Claude Haiku 5.5 from the sources below · 2026-11-04
Red Hat 1 advisory
- RHSA-2026:82247 Released 2026-10-13 · Red Hat rating ModerateRed Hat Hardened Images RPMs bug fix and enhancement update
- Red Hat Hardened Images openssh-10.5p1-1.2.hum1@aarch64, openssh-10.5p1-1.2.hum1@s390x, openssh-10.5p1-1.2.hum1@src +19
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Advisory ·
Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6 and 5 more products — RHSA-2026:82247
3 records Highest priority Priority LOW 3 LOW
Other records, highest priority first
- TI-2026-74643 Path traversal in OpenSSH sftp lets a server write outside the target directoryPriority LOW 29
- TI-2026-74644 OpenSSH passes unescaped username characters into the shell via %uPriority LOW 24
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Hardened Images | Fixed | RHSA-2026:82247 |
Not affected: 8 products
- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
- Red Hat Hardened Images
- Red Hat OpenShift Container Platform 4
- Red Hat OpenShift Container Platform 5
Timeline
- 2026-10-15 Threatist record created from CVE-2026-110926
- 2026-10-16 Alias added: GHSA-3j57-3pc4-v67v
- 2026-10-16 Fix available: RHSA-2026:82247 · Red Hat
- 2026-10-16 Fix available: Red Hat Hardened Images · Red Hat
- 2026-10-16 CVSS score added · Red Hat
- 2026-10-20 Affected versions changed · CNA
- 2026-10-20 Affected versions changed · Red Hat
- 2026-11-04 Affected versions changed · Red Hat
References
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- TI-2018-16080 A code execution vulnerability exists in the Stapler web framework used by Jenkins 2.153… KEVCVSS 3.1CRITICAL 9.8
Sources
- CVE-2026-110926 · CVE Program
- CVE-2026-110926 · NVD
- FIRST EPSS
- GHSA-3j57-3pc4-v67v · GitHub Advisory Database · CC BY 4.0
- CVE-2026-110926 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences