CVE-2026-56855

HIGHPre-NVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under CISA-ADP (Vulnrichment) CVSS v3.1 (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 68% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: cisa-adp, epss
Trending — 3 sources updated this week
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.5Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Previously, after a channel has been established, a malicious peer could send crafted messages that would deadlock the entire connection. Now, we handle all RFC 4254 channel messages; global requests are handled explicitly. Then, treat all other messages as a protocol error and tear the connection down instead of buffering and blocking.

CVSS v3
7.5
EG Score
7.5(medium)
EG Risk
49(Track)
EG Risk 49/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity75% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
32%
KEV
Not listed

Published

September 2, 2026

Last Modified

September 4, 2026

Advisory Details (4)

Auto-updated Sep 3, 2026
No patch confirmed yet.
generic

GO-2026-6355 - Go Packages

https://pkg.go.dev/vuln/GO-2026-6355
generic
https://groups.google.com/g/golang-announce/c/1y3fb2np35U
generic
https://go.dev/cl/826524
generic

x/crypto/ssh: prevent DoS on deadlocked established channel · Issue #81317 · golang/go · GitHub

https://go.dev/issue/81317

Vendor Advisories for CVE-2026-56855(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(4 across 4 ecosystems)
Debian:12(1)
PackageVulnerable rangeFixed inDependents
golang-go.crypto1:0.10.0-1 ... 1:0.56.0-1 (36 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
golang-go.crypto1:0.25.0-1 ... 1:0.56.0-1 (21 versions)——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
golang-go.crypto1:0.25.0-1 ... 1:0.55.0-1 (20 versions)1:0.56.0-1—
Go(1)
PackageVulnerable rangeFixed inDependents
golang.org/x/crypto—0.56.0—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 26× in last 7d / 52× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. 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. Most recent first.

  1. 2026-09-19 01:08 UTCEG score recompute
  2. 2026-09-19 01:08 UTCVendor advisory
  3. 2026-09-18 19:28 UTCEPSS rescore
  4. 2026-09-18 12:33 UTCVendor advisory
  5. 2026-09-17 23:57 UTCEG score recompute
  6. 2026-09-17 23:57 UTCVendor advisory
  7. 2026-09-17 19:31 UTCEPSS rescore
  8. 2026-09-17 10:17 UTCVendor advisory
  9. 2026-09-16 21:42 UTCEG score recompute
  10. 2026-09-16 21:42 UTCVendor advisory
  11. 2026-09-16 14:08 UTCEPSS rescore
  12. 2026-09-16 09:04 UTCEG score recompute
  13. 2026-09-16 09:04 UTCVendor advisory
  14. 2026-09-16 05:15 UTCEPSS rescore
  15. 2026-09-15 19:44 UTCVendor advisory
  16. 2026-09-15 07:00 UTCEG score recompute
  17. 2026-09-15 07:00 UTCVendor advisory
  18. 2026-09-15 03:11 UTCEPSS rescore
  19. 2026-09-14 18:24 UTCVendor advisory
  20. 2026-09-14 05:12 UTCEG score recompute
  21. 2026-09-14 05:12 UTCVendor advisory
  22. 2026-09-13 16:47 UTCEPSS rescore
  23. 2026-09-13 16:37 UTCVendor advisory
  24. 2026-09-13 04:02 UTCVendor advisory
  25. 2026-09-12 15:26 UTCEG score recompute
Show 27 more
  1. 2026-09-12 15:26 UTCVendor advisory
  2. 2026-09-12 02:48 UTCEG score recompute
  3. 2026-09-12 02:48 UTCVendor advisory
  4. 2026-09-11 14:53 UTCEPSS rescore
  5. 2026-09-11 14:13 UTCEG score recompute
  6. 2026-09-10 13:01 UTCEG score recompute
  7. 2026-09-10 09:35 UTCEPSS rescore
  8. 2026-09-09 11:47 UTCVendor advisory
  9. 2026-09-08 23:11 UTCEG score recompute
  10. 2026-09-08 23:11 UTCVendor advisory
  11. 2026-09-08 22:01 UTCEPSS rescore
  12. 2026-09-08 09:59 UTCVendor advisory
  13. 2026-09-07 20:21 UTCEG score recompute
  14. 2026-09-07 20:21 UTCVendor advisory
  15. 2026-09-07 16:01 UTCEPSS rescore
  16. 2026-09-07 07:45 UTCVendor advisory
  17. 2026-09-06 19:09 UTCEG score recompute
  18. 2026-09-06 13:47 UTCEPSS rescore
  19. 2026-09-05 17:55 UTCEG score recompute
  20. 2026-09-04 16:43 UTCEG score recompute
  21. 2026-09-04 05:35 UTCEG score recompute
  22. 2026-09-04 05:07 UTCEPSS rescore
  23. 2026-09-03 14:20 UTCEG score recompute▲ 7.50
  24. 2026-09-03 14:18 UTCMITRE cvelistV5CVSS v3 → 7.5 · severity → HIGH
  25. 2026-09-02 20:19 UTCNVD update
  26. 2026-09-02 19:46 UTCEG score recompute
  27. 2026-09-02 19:45 UTCMITRE cvelistV5first tracked

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-56855?
CVE-2026-56855 is a high vulnerability published on September 2, 2026. Previously, after a channel has been established, a malicious peer could send crafted messages that would deadlock the entire connection. Now, we handle all RFC 4254 channel messages; global requests are handled explicitly. Then, treat all other messages as a protocol error and tear the connection…
When was CVE-2026-56855 disclosed?
CVE-2026-56855 was first published in the National Vulnerability Database on September 2, 2026, with the most recent update on September 4, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-56855 actively exploited?
CVE-2026-56855 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 68.3% of all scored CVEs.
What is the CVSS score of CVE-2026-56855?
CVE-2026-56855 has a CVSS v3.1 base score of 7.5 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-56855?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-56855, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-56855

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