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.
CVE-2026-55655
“—” beside the score: it is equal to NVD's CVSS score.
This medium-severity CVE scores 6.1 under NVD CVSS v3. EPSS exploit probability: 0.1% (2nd percentile of EPSS-scored CVEs). GitHub Security Advisory CVSS 5.0 is lower than this score; a lower GitHub score revises it only when its advisory is newer than the CVE record's last change, and this advisory (published 2026-06-23) is not newer than that change (2026-10-30), so it does not.
Also known asEUVD-2026-38413 (ENISA EUVD) · GHSA-wcvf-3x75-j4c6 (GitHub Security Advisories)Source: ENISA EUVD
- Lower severity and no public exploit yet
A fix is available — apply it.
- CVSS v3
- 6.1
- EG Score
- 6.1MEDIUMmedium confidence
- EG Risk
- 27EG Risk 27/100
EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.
How it’s computed (value × EchelonGraph’s weight)Severity61% × 45%Impact severity (EG Severity): CVSS 6.1 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation0.1% × 40%FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.Automatability0% × 15%CISA's SSVC Automatable value: no (Vulnrichment).SSVC (CISA's decision table, applied by EchelonGraph): Track at every mission impact level.Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.Action: A fix is available. Apply it within your standard update timelines. - EPSS PROB
- 0.1%
- EPSS %ILE
- 2nd
- KEV
- Not listed
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (6.1): severity, escalated by confirmed exploitation. This CVE's 6.1 is its impact severity (EG Severity), not escalated.
- EG Severity
- 6.1 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.NVD CVSS v3 · CVSS v3.0 or v3.1
- EG Likelihood
- 0.1% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-29). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at every mission impact level.CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.
A fix is available. Apply it within your standard update timelines.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it
Published
June 23, 2026
Last Modified
October 30, 2026
Advisory Details (2)
Auto-updated Jun 23, 20262462250 – (CVE-2026-55655) CVE-2026-55655 openssh: Local MITM of X11 forwarding via abstract UNIX socket pre-binding in Red Hat Enterprise Linux OpenSSH client versions
https://bugzilla.redhat.com/show_bug.cgi?id=2462250cve-details
https://access.redhat.com/security/cve/CVE-2026-55655Vendor Advisories for CVE-2026-55655(20)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
- RHSA-2026:91232Red Hat Product SecurityCritical
Red Hat Security Advisory: Red Hat AI Base Images 3.0.7 (CPU)
- RHSA-2026:89739Red Hat Product SecurityHigh
Red Hat Security Advisory: openssh security update
- RHSA-2026:82923Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat AI Base Images 3.2.5 (ROCm 7.0)
- RHSA-2026:82922Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat AI Base Images 3.2.5 (ROCm 6.4)
- RHSA-2026:82921Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat AI Base Images 3.2.5 (CUDA 12.9)
- RHSA-2026:82920Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat AI Base Images 3.2.5 (TPU)
- RHSA-2026:82918Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat AI Base Images 3.5.4 (CUDA 12.9)
- RHSA-2026:82917Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat AI Base Images 3.3.6 (Spyre)
- +12 more
Patch Availability(30)
Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.
Affected Packages
(4 across 4 ecosystems)
Debian:11(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssh | 1:10.0p1-1 ... 1:9.9p2-2 (86 versions) |
| — |
Debian:12(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssh | 1:10.0p1-1 ... 1:9.9p2-2 (75 versions) |
| — |
Debian:13(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssh | 1:10.0p1-7 ... 1:10.4p1-4 (29 versions) |
| — |
Debian:14(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssh | 1:10.0p1-7 ... 1:10.4p1-4 (25 versions) |
| — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
All Vendor Advisories
(25)
Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.
- Microsoft MSRCCVE-2026-556552026-06-27
Openssh: local mitm of x11 forwarding via abstract unix socket pre-binding in red hat enterprise linux openssh client versions
- Red HatRHSA-2026:36759MODERATE2026-06-22
RHSA-2026:36759 — Moderate
- Red HatRHSA-2026:47755MODERATE2026-06-22
RHSA-2026:47755 — Moderate
- Red HatRHSA-2026:47756MODERATE2026-06-22
RHSA-2026:47756 — Moderate
- Red HatRHSA-2026:47757MODERATE2026-06-22
RHSA-2026:47757 — Moderate
- Red HatRHSA-2026:54387MODERATE2026-06-22
RHSA-2026:54387 — Moderate
- Red HatRHSA-2026:58981MODERATE2026-06-22
RHSA-2026:58981 — Moderate
- Red HatRHSA-2026:76748MODERATE2026-06-22
RHSA-2026:76748 — Moderate
- Red HatRHSA-2026:76993MODERATE2026-06-22
RHSA-2026:76993 — Moderate
- Red HatRHSA-2026:80513MODERATE2026-06-22
RHSA-2026:80513 — Moderate
- Red HatRHSA-2026:82749MODERATE2026-06-22
RHSA-2026:82749 — Moderate
- Red HatRHSA-2026:82750MODERATE2026-06-22
RHSA-2026:82750 — Moderate
- Red HatRHSA-2026:82751MODERATE2026-06-22
RHSA-2026:82751 — Moderate
- Red HatRHSA-2026:82752MODERATE2026-06-22
RHSA-2026:82752 — Moderate
- Red HatRHSA-2026:82753MODERATE2026-06-22
RHSA-2026:82753 — Moderate
- Red HatRHSA-2026:82754MODERATE2026-06-22
RHSA-2026:82754 — Moderate
- Red HatRHSA-2026:82755MODERATE2026-06-22
RHSA-2026:82755 — Moderate
- Red HatRHSA-2026:82756MODERATE2026-06-22
RHSA-2026:82756 — Moderate
- Red HatRHSA-2026:82757MODERATE2026-06-22
RHSA-2026:82757 — Moderate
- Red HatRHSA-2026:82758MODERATE2026-06-22
RHSA-2026:82758 — Moderate
- Red HatRHSA-2026:82759MODERATE2026-06-22
RHSA-2026:82759 — Moderate
- Red HatRHSA-2026:82761MODERATE2026-06-22
RHSA-2026:82761 — Moderate
- Red HatRHSA-2026:82762MODERATE2026-06-22
RHSA-2026:82762 — Moderate
- Red HatRHSA-2026:82763MODERATE2026-06-22
RHSA-2026:82763 — Moderate
- Red HatRHSA-2026:82897MODERATE2026-06-22
RHSA-2026:82897 — Moderate
Data Freshness Timeline
(refreshed 15× in last 7d / 70× in last 30d)
Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.
Showing the most recent 100 of 286 refreshes on record for this CVE.
A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 186 oldest rows on record are not shown and were not checked, so the counts can still include repeats.
- 2026-11-02 16:45 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
- 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
- 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
- 2026-10-30 08:26 UTCVendor advisory
- 2026-10-30 08:26 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub CVSS 5.0
- 2026-10-30 07:51 UTCEG score recompute
- 2026-10-30 07:51 UTCVendor advisory
- 2026-10-30 07:51 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub CVSS 5.0
- 2026-10-29 23:26 UTCVendor advisory
- 2026-10-29 23:26 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub CVSS 5.0
- 2026-10-29 22:26 UTCEG score recompute
- 2026-10-29 22:26 UTCVendor advisory
- 2026-10-29 22:26 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub CVSS 5.0
- 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
- 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
- 2026-10-26 16:31 UTCEPSS rescoreEPSS <0.1% · below the 1st percentile
- 2026-10-26 04:30 UTCVendor advisory
- 2026-10-26 04:29 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub CVSS 5.0
- 2026-10-26 03:35 UTCEG score recompute
- 2026-10-26 03:35 UTCVendor advisory
- 2026-10-26 03:35 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub CVSS 5.0
- 2026-10-25 16:33 UTCEPSS rescoreEPSS <0.1% · below the 1st percentile
- 2026-10-25 14:18 UTCEG score recompute
- 2026-10-24 16:33 UTCEPSS rescoreEPSS <0.1% · below the 1st percentile
- 2026-10-22 16:34 UTCEPSS rescoreEPSS <0.1% · below the 1st percentile
Show 75 moreShow fewer
- 2026-10-21 16:33 UTCEPSS rescoreEPSS <0.1% · below the 1st percentile
- 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
- 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
- 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
- 2026-10-18 03:30 UTCEG score recompute
- 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
- 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
- 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
- 2026-10-14 20:44 UTCVendor advisory
- 2026-10-14 20:43 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub CVSS 5.0
- 2026-10-14 19:36 UTCEG score recompute
- 2026-10-14 19:36 UTCVendor advisory
- 2026-10-14 19:36 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub CVSS 5.0
- 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
- 2026-10-14 07:26 UTCEG score recompute
- 2026-10-14 07:26 UTCVendor advisory
- 2026-10-14 07:26 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub CVSS 5.0
- 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
- 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
- 2026-10-12 15:55 UTCEG score recompute
- 2026-10-12 08:27 UTCVendor advisory
- 2026-10-12 08:26 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub CVSS 5.0
- 2026-10-12 08:08 UTCEG score recompute
- 2026-10-12 08:08 UTCVendor advisory
- 2026-10-12 08:08 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub CVSS 5.0
- 2026-10-11 19:38 UTCEG score recompute
- 2026-10-11 16:54 UTCEG score recompute
- 2026-10-11 14:16 UTCEG score recompute
- 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
- 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
- 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
- 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
- 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
- 2026-10-07 03:32 UTCVendor advisory
- 2026-10-07 03:31 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub CVSS 5.0
- 2026-10-07 02:47 UTCVendor advisory
- 2026-10-07 02:47 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub CVSS 5.0
- 2026-10-06 16:21 UTCVendor advisory
- 2026-10-06 16:21 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub CVSS 5.0
- 2026-10-06 15:38 UTCEG score recompute
- 2026-10-06 15:38 UTCVendor advisory
- 2026-10-06 15:38 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub CVSS 5.0
- 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.1% · 1st percentile
- 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.1% · 1st percentile
- 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.1% · 1st percentile
- 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.1% · 1st percentile
- 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.1% · 1st percentile
- 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.1% · 1st percentile
- 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.1% · 1st percentile
- 2026-09-29 15:22 UTCEPSS rescoreEPSS 0.1% · 1st percentile
- 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.1% · 1st percentile
- 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.1% · 1st percentile
- 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.1% · 1st percentile
- 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.1% · 1st percentile
- 2026-09-23 17:54 UTCEPSS rescoreEPSS <0.1% · below the 1st percentile
- 2026-09-18 11:12 UTCEG score recompute
- 2026-09-18 11:12 UTCVendor advisory
- 2026-09-18 11:12 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub CVSS 5.0
- 2026-09-17 19:31 UTCEPSS rescoreEPSS <0.1% · below the 1st percentile
- 2026-09-16 14:08 UTCEPSS rescoreEPSS <0.1% · below the 1st percentile
- 2026-09-16 05:15 UTCEPSS rescoreEPSS <0.1% · below the 1st percentile
- 2026-09-13 16:47 UTCEPSS rescoreEPSS <0.1% · below the 1st percentile
- 2026-09-13 12:28 UTCEG score recompute
- 2026-09-13 12:28 UTCVendor advisory
- 2026-09-13 12:28 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub CVSS 5.0
- 2026-09-11 14:53 UTCEPSS rescoreEPSS <0.1% · below the 1st percentile
- 2026-09-10 09:35 UTCEPSS rescoreEPSS <0.1% · below the 1st percentile
- 2026-09-08 22:01 UTCEPSS rescoreEPSS <0.1% · below the 1st percentile
- 2026-09-06 13:47 UTCEPSS rescoreEPSS <0.1% · below the 1st percentile
- 2026-09-04 05:06 UTCEPSS rescoreEPSS <0.1% · below the 1st percentile
- 2026-09-02 14:12 UTCEPSS rescoreEPSS <0.1% · below the 1st percentile
- 2026-09-01 13:54 UTCEPSS rescoreEPSS <0.1% · below the 1st percentile
- 2026-09-01 09:34 UTCVendor advisory
- 2026-09-01 09:34 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub CVSS 5.0
- 2026-09-01 08:56 UTCVendor advisory
Related CVEs(same product + same vendor + same CWE)
Same product
10 shownDebian:11:openssh
- CVE-2003-0786EG 10.0HIGH
- CVE-2003-0693EG 10.0EPSS p96HIGH
- CVE-2002-0640EG 10.0EPSS p98HIGH
- CVE-2023-51385NVD 6.5EG 9.8EPSS p97CRITICAL
- CVE-2023-38408EG 9.8EPSS p100CRITICAL
- CVE-2016-1908EG 9.8EPSS p97CRITICAL
- CVE-2002-0639EG 9.8EPSS p97CRITICAL
- CVE-2026-60002EG 9.4CRITICAL
- CVE-2023-48795NVD 5.9EG 9.0EPSS p100CRITICAL
- CVE-2018-15473NVD 5.3EG 9.0EPSS p100CRITICAL
Same vendor
10 shownredhat:RHSA-2026:36759 · redhat:RHSA-2026:47756 · redhat:RHSA-2026:76748
Frequently asked(5)
What is CVE-2026-55655?
When was CVE-2026-55655 made public?
Is CVE-2026-55655 actively exploited?
What is the CVSS score of CVE-2026-55655?
How do I remediate CVE-2026-55655?
Dependency Blast Radius
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