CVE-2026-56865

HIGHPre-NVD 8.48.4—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.4 under CISA-ADP (Vulnrichment) CVSS v3.1 (NVD's own analysis pending). EPSS exploit probability: 0.1%, top 99% 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
8.4EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.4Exploit: None knownExposed: 0

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

A malicious GOPROXY was previously capable of forging up to two sumdb tiles that allow for a requested module to bypass the GOSUMDB check and persist attacker-controlled module content to a local Go module cache. This attack allows for a malicious GOPROXY to serve malicious module content that cannot be detected by evaluating the transparency log. All tiles are now correctly verified against their parents. In order to determine if you have been affected: rm -r go.sum go.work.sum vendor/ && go mod tidy

CVSS v3
8.4
EG Score
8.4(medium)
EG Risk
38(Track)
EG Risk 38/100SSVC: 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
Severity84% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
1%
KEV
Not listed

Published

August 13, 2026

Last Modified

August 14, 2026

Advisory Details (5)

Auto-updated Aug 14, 2026
No patch confirmed yet.
generic

GO-2026-6179 - Go Packages

https://pkg.go.dev/vuln/GO-2026-6179
generic
https://go.dev/cl/815020
generic
https://go.dev/cl/814960
generic
https://groups.google.com/g/golang-announce/c/94pEornpRlI
generic

x/mod/sumdb/tlog: fix transparency log tile verification bypass · Issue #80744 · golang/go · GitHub

https://go.dev/issue/80744

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 10× in last 7d / 26× 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. 2026-08-26 14:46 UTCEPSS rescore
  2. 2026-08-25 23:18 UTCEG score recompute
  3. 2026-08-25 13:49 UTCEPSS rescore
  4. 2026-08-24 22:46 UTCEG score recompute
  5. 2026-08-24 10:31 UTCEG score recompute
  6. 2026-08-23 09:59 UTCEG score recompute
  7. 2026-08-23 00:19 UTCEPSS rescore
  8. 2026-08-21 08:58 UTCEG score recompute
  9. 2026-08-20 22:55 UTCEPSS rescore
  10. 2026-08-19 20:12 UTCEG score recompute
  11. 2026-08-19 17:04 UTCEPSS rescore
  12. 2026-08-18 19:38 UTCEG score recompute
  13. 2026-08-18 13:48 UTCEPSS rescore
  14. 2026-08-17 19:07 UTCEG score recompute
  15. 2026-08-17 13:47 UTCEPSS rescore
  16. 2026-08-16 17:37 UTCEG score recompute
  17. 2026-08-16 14:56 UTCEPSS rescore
  18. 2026-08-16 05:17 UTCEG score recompute
  19. 2026-08-16 02:14 UTCEPSS rescore
  20. 2026-08-15 04:47 UTCEG score recompute
  21. 2026-08-15 01:30 UTCEPSS rescore
  22. 2026-08-14 15:39 UTCEG score recompute▲ 8.40
  23. 2026-08-14 15:38 UTCMITRE cvelistV5CVSS v3 → 8.4 · severity → HIGH
  24. 2026-08-13 22:25 UTCNVD update
  25. 2026-08-13 22:09 UTCEG score recompute
Show 1 more
  1. 2026-08-13 22:09 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-56865?
CVE-2026-56865 is a high vulnerability published on August 13, 2026. A malicious GOPROXY was previously capable of forging up to two sumdb tiles that allow for a requested module to bypass the GOSUMDB check and persist attacker-controlled module content to a local Go module cache. This attack allows for a malicious GOPROXY to serve malicious module content that…
When was CVE-2026-56865 disclosed?
CVE-2026-56865 was first published in the National Vulnerability Database on August 13, 2026, with the most recent update on August 14, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-56865 actively exploited?
CVE-2026-56865 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 98.8% of all scored CVEs.
What is the CVSS score of CVE-2026-56865?
CVE-2026-56865 has a CVSS v3.1 base score of 8.4 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-56865?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-56865, 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

Explore the affected products and dependency analysis for CVE-2026-56865

Explore →

Is Your Infrastructure Affected by CVE-2026-56865?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs