CVE-2026-55655

MEDIUMNVD 6.16.1
EchelonGraph scoreMEDIUM confidence

“—” 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 (2026-11-12), so it does not.

Triggered by: Headline CVSS from NVD CVSS v3
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3

Also known asEUVD-2026-38413 (ENISA EUVD) · GHSA-wcvf-3x75-j4c6 (GitHub Security Advisories)Source: ENISA EUVD

6.1EG
EchelonGraph verdictMonitorRemediate within your standard update timelines (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.1%CVSS: 6.1Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

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.

CVSS v3
6.1
EG Score
6.1MEDIUMmedium confidence
EG Risk
27
EG 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 2026-11-11). 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

November 12, 2026

Advisory Details (2)

Auto-updated Jun 23, 2026
Patch available. Sources: redhat.
Red Hat

2462250 – (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=2462250
Red HatMentions a patch (unverified)

cve-details

https://access.redhat.com/security/cve/CVE-2026-55655

Vendor 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.

Patch Availability(30)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatrhai/base-image-cpu-rhel9:17930420722026-10-27redhat
redhatopenssh-0:8.7p1-30.el9_2.132026-10-26redhat
redhatrhai/base-image-spyre-rhel9:17918192522026-10-14redhat
redhatrhai/base-image-gaudi-rhel9:17918187492026-10-14redhat
redhatrhai/base-image-spyre-rhel9:17918186022026-10-14redhat
redhatrhai/base-image-cuda-12.9-rhel9:17918191042026-10-14redhat
redhatrhai/base-image-rocm-6.4-rhel9:17918814872026-10-14redhat
redhatrhai/base-image-neuron-rhel9:17918189792026-10-14redhat
redhatrhai/base-image-rubin-rhel9:17918203332026-10-14redhat
redhatrhai/base-image-tpu-rhel9:17918184962026-10-14redhat
redhatrhai/base-image-tpu-rhel9:17918189012026-10-14redhat
redhatrhai/base-image-rocm-rhel9:17918185022026-10-14redhat
redhatrhai/base-image-rocm-rhel9:17918187782026-10-14redhat
redhatrhai/base-image-tpu-rhel9:17918185122026-10-14redhat
redhatrhai/base-image-rocm-rhel9:17918185122026-10-14redhat
redhatrhai/base-image-tpu-rhel9:17918817692026-10-14redhat
redhatrhai/base-image-cpu-rhel9:17918192062026-10-14redhat
redhatrhai/base-image-rocm-6.4-rhel9:17918187822026-10-14redhat
redhatrhai/base-image-cuda-12.9-rhel9:17918186272026-10-14redhat
redhatrhai/base-image-cpu-rhel9:17918188742026-10-14redhat
redhatrhai/base-image-cuda-13.0-rhel9:17918186622026-10-14redhat
redhatrhai/base-image-rocm-7.0-rhel9:17918187902026-10-14redhat
redhatrhai/base-image-spyre-rhel9:17918185052026-10-14redhat
redhatrhai/base-image-cuda-rhel9:17918185902026-10-14redhat
redhatrhai/base-image-gaudi-rhel9:17918814862026-10-14redhat
redhatrhai/base-image-cuda-13.0-rhel9:17918855052026-10-14redhat
redhatrhai/base-image-neuron-rhel9:17918187922026-10-14redhat
redhatrhai/base-image-cuda-rhel9:17918185872026-10-14redhat
redhatrhai/base-image-spyre-rhel9:17918188772026-10-14redhat
redhatrhai/base-image-rocm-7.1-rhel9:17918833152026-10-14redhat

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)
PackageVulnerable rangeFix by version rangeDependents
openssh1:10.0p1-1 ... 1:9.9p2-2 (86 versions)
  • every version on: no fix on record
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
openssh1:10.0p1-1 ... 1:9.9p2-2 (75 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
openssh1:10.0p1-7 ... 1:10.4p1-4 (29 versions)
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
openssh1:10.0p1-7 ... 1:10.4p1-4 (25 versions)
  • every version on: no fix on record
—

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.

Data Freshness Timeline

(refreshed 11× in last 7d / 49× 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 its CVE.org record (CNA or CISA ADP). 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). "EchelonGraph re-scored" is our own recompute of this CVE's score, not an update from a source, and is not counted in the refreshes above. Most recent first.

Showing the most recent 100 of 307 rows 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 207 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-13 16:53 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  2. 2026-11-12 16:34 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  3. 2026-11-12 11:28 UTCVendor advisory
  4. 2026-11-12 11:28 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub severity MODERATE · GitHub CVSS 5.0
  5. 2026-11-12 10:57 UTCEchelonGraph re-scored
  6. 2026-11-12 10:57 UTCVendor advisory
  7. 2026-11-12 10:57 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub severity MODERATE · GitHub CVSS 5.0
  8. 2026-11-11 16:40 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  9. 2026-11-10 16:44 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  10. 2026-11-09 16:35 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  11. 2026-11-08 16:40 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  12. 2026-11-07 16:39 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  13. 2026-11-06 16:38 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  14. 2026-11-05 22:29 UTCVendor advisory
  15. 2026-11-05 22:29 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub severity MODERATE · GitHub CVSS 5.0
  16. 2026-11-05 21:53 UTCEchelonGraph re-scored
  17. 2026-11-05 21:53 UTCVendor advisory
  18. 2026-11-05 21:53 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub severity MODERATE · GitHub CVSS 5.0
  19. 2026-11-05 16:38 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  20. 2026-11-04 16:35 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  21. 2026-11-03 16:48 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  22. 2026-11-02 16:45 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  23. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  24. 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  25. 2026-10-30 08:26 UTCVendor advisory
Show 75 more
  1. 2026-10-30 08:26 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub CVSS 5.0
  2. 2026-10-30 07:51 UTCEchelonGraph re-scored
  3. 2026-10-30 07:51 UTCVendor advisory
  4. 2026-10-30 07:51 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub CVSS 5.0
  5. 2026-10-29 23:26 UTCVendor advisory
  6. 2026-10-29 23:26 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub CVSS 5.0
  7. 2026-10-29 22:26 UTCEchelonGraph re-scored
  8. 2026-10-29 22:26 UTCVendor advisory
  9. 2026-10-29 22:26 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub CVSS 5.0
  10. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  11. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  12. 2026-10-26 16:31 UTCEPSS rescoreEPSS <0.1% · below the 1st percentile
  13. 2026-10-26 04:30 UTCVendor advisory
  14. 2026-10-26 04:29 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub CVSS 5.0
  15. 2026-10-26 03:35 UTCEchelonGraph re-scored
  16. 2026-10-26 03:35 UTCVendor advisory
  17. 2026-10-26 03:35 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub CVSS 5.0
  18. 2026-10-25 16:33 UTCEPSS rescoreEPSS <0.1% · below the 1st percentile
  19. 2026-10-25 14:18 UTCEchelonGraph re-scored
  20. 2026-10-24 16:33 UTCEPSS rescoreEPSS <0.1% · below the 1st percentile
  21. 2026-10-22 16:34 UTCEPSS rescoreEPSS <0.1% · below the 1st percentile
  22. 2026-10-21 16:33 UTCEPSS rescoreEPSS <0.1% · below the 1st percentile
  23. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  24. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  25. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  26. 2026-10-18 03:30 UTCEchelonGraph re-scored
  27. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  28. 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  29. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  30. 2026-10-14 20:44 UTCVendor advisory
  31. 2026-10-14 20:43 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub CVSS 5.0
  32. 2026-10-14 19:36 UTCEchelonGraph re-scored
  33. 2026-10-14 19:36 UTCVendor advisory
  34. 2026-10-14 19:36 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub CVSS 5.0
  35. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  36. 2026-10-14 07:26 UTCEchelonGraph re-scored
  37. 2026-10-14 07:26 UTCVendor advisory
  38. 2026-10-14 07:26 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub CVSS 5.0
  39. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  40. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  41. 2026-10-12 15:55 UTCEchelonGraph re-scored
  42. 2026-10-12 08:27 UTCVendor advisory
  43. 2026-10-12 08:26 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub CVSS 5.0
  44. 2026-10-12 08:08 UTCEchelonGraph re-scored
  45. 2026-10-12 08:08 UTCVendor advisory
  46. 2026-10-12 08:08 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub CVSS 5.0
  47. 2026-10-11 19:38 UTCEchelonGraph re-scored
  48. 2026-10-11 16:54 UTCEchelonGraph re-scored
  49. 2026-10-11 14:16 UTCEchelonGraph re-scored
  50. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  51. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  52. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  53. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  54. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  55. 2026-10-07 03:32 UTCVendor advisory
  56. 2026-10-07 03:31 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub CVSS 5.0
  57. 2026-10-07 02:47 UTCVendor advisory
  58. 2026-10-07 02:47 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub CVSS 5.0
  59. 2026-10-06 16:21 UTCVendor advisory
  60. 2026-10-06 16:21 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub CVSS 5.0
  61. 2026-10-06 15:38 UTCEchelonGraph re-scored
  62. 2026-10-06 15:38 UTCVendor advisory
  63. 2026-10-06 15:38 UTCGHSA enrichmentGHSA-wcvf-3x75-j4c6 · GitHub CVSS 5.0
  64. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  65. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  66. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  67. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  68. 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  69. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  70. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  71. 2026-09-29 15:22 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  72. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  73. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  74. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  75. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.1% · 1st percentile

Related CVEs(same product + same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-55655?
CVE-2026-55655 is a medium-severity vulnerability; its CVE record was published on June 23, 2026. 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…
When was CVE-2026-55655 made public?
CVE-2026-55655 was made public on June 22, 2026: that is the date its CVE record's CNA, Red Hat, Inc., gives for when the vulnerability was made public. The CVE record itself was published on June 23, 2026. EchelonGraph's copy of the record carries a last-modified date of November 12, 2026; the record at its source may have been updated since.
Is CVE-2026-55655 actively exploited?
CVE-2026-55655 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.1% probability of exploitation in the next 30 days (2nd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-55655?
CVE-2026-55655 has a CVSS v3 base score of 6.1 (NVD).
How do I remediate CVE-2026-55655?
A fix for CVE-2026-55655 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-55655 are linked in the Vendor Advisories panel on this page.

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