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
Trending — 3 sources updated this week
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

September 3, 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

Affected Packages

(7 across 4 ecosystems)
Debian:14(3)
PackageVulnerable rangeFixed inDependents
golang-1.251.25.0-1 ... 1.25.9-1 (20 versions)——
golang-1.261.26.0-1 ... 1.26~rc3-2 (16 versions)1.26.6-1—
golang-1.271.27~rc1-1, 1.27~rc2-11.27~rc3-1—
Go(2)
PackageVulnerable rangeFixed inDependents
golang.org/x/mod—0.40.0—
toolchain—1.27.0-rc.3—
Debian:12(1)
PackageVulnerable rangeFixed inDependents
golang-1.191.19.10-1 ... 1.19.9-1 (12 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
golang-1.241.24.12-1 ... 1.24.9-1 (10 versions)——

Weakness Classification(1)

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

All Vendor Advisories

(1)

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 22× in last 7d / 61× 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 01:05 UTCEG score recompute
  2. 2026-09-19 01:05 UTCVendor advisory
  3. 2026-09-18 19:28 UTCEPSS rescore
  4. 2026-09-18 12:48 UTCVendor advisory
  5. 2026-09-18 00:24 UTCEG score recompute
  6. 2026-09-18 00:24 UTCVendor advisory
  7. 2026-09-17 19:31 UTCEPSS rescore
  8. 2026-09-17 12:06 UTCVendor advisory
  9. 2026-09-16 23:50 UTCEG score recompute
  10. 2026-09-16 23:50 UTCVendor advisory
  11. 2026-09-16 14:08 UTCEPSS rescore
  12. 2026-09-16 10:27 UTCVendor advisory
  13. 2026-09-15 21:53 UTCVendor advisory
  14. 2026-09-15 09:03 UTCEG score recompute
  15. 2026-09-15 09:03 UTCVendor advisory
  16. 2026-09-15 03:11 UTCEPSS rescore
  17. 2026-09-14 20:47 UTCVendor advisory
  18. 2026-09-14 08:31 UTCVendor advisory
  19. 2026-09-13 20:16 UTCVendor advisory
  20. 2026-09-13 08:00 UTCVendor advisory
  21. 2026-09-12 19:45 UTCVendor advisory
  22. 2026-09-12 07:29 UTCVendor advisory
  23. 2026-09-11 19:13 UTCEG score recompute
  24. 2026-09-11 19:13 UTCVendor advisory
  25. 2026-09-11 14:53 UTCEPSS rescore
Show 53 more
  1. 2026-09-10 18:33 UTCEG score recompute
  2. 2026-09-10 09:35 UTCEPSS rescore
  3. 2026-09-09 17:41 UTCVendor advisory
  4. 2026-09-09 04:51 UTCEG score recompute
  5. 2026-09-09 04:51 UTCVendor advisory
  6. 2026-09-08 22:01 UTCEPSS rescore
  7. 2026-09-08 04:42 UTCVendor advisory
  8. 2026-09-07 16:27 UTCVendor advisory
  9. 2026-09-06 20:25 UTCEG score recompute
  10. 2026-09-06 13:47 UTCEPSS rescore
  11. 2026-09-05 19:46 UTCEG score recompute
  12. 2026-09-04 19:14 UTCEG score recompute
  13. 2026-09-04 06:12 UTCEG score recompute
  14. 2026-09-04 05:07 UTCEPSS rescore
  15. 2026-09-01 23:33 UTCEG score recompute
  16. 2026-09-01 13:54 UTCEPSS rescore
  17. 2026-09-01 11:14 UTCEG score recompute
  18. 2026-09-01 04:40 UTCEPSS rescore
  19. 2026-08-30 20:54 UTCEG score recompute
  20. 2026-08-30 19:17 UTCEPSS rescore
  21. 2026-08-30 08:39 UTCEG score recompute
  22. 2026-08-30 01:22 UTCEPSS rescore
  23. 2026-08-29 06:58 UTCEG score recompute
  24. 2026-08-28 21:42 UTCEPSS rescore
  25. 2026-08-28 00:49 UTCEG score recompute
  26. 2026-08-27 14:25 UTCEPSS rescore
  27. 2026-08-26 23:51 UTCEG score recompute
  28. 2026-08-26 14:46 UTCEPSS rescore
  29. 2026-08-25 23:18 UTCEG score recompute
  30. 2026-08-25 13:49 UTCEPSS rescore
  31. 2026-08-24 22:46 UTCEG score recompute
  32. 2026-08-24 10:31 UTCEG score recompute
  33. 2026-08-23 09:59 UTCEG score recompute
  34. 2026-08-23 00:19 UTCEPSS rescore
  35. 2026-08-21 08:58 UTCEG score recompute
  36. 2026-08-20 22:55 UTCEPSS rescore
  37. 2026-08-19 20:12 UTCEG score recompute
  38. 2026-08-19 17:04 UTCEPSS rescore
  39. 2026-08-18 19:38 UTCEG score recompute
  40. 2026-08-18 13:48 UTCEPSS rescore
  41. 2026-08-17 19:07 UTCEG score recompute
  42. 2026-08-17 13:47 UTCEPSS rescore
  43. 2026-08-16 17:37 UTCEG score recompute
  44. 2026-08-16 14:56 UTCEPSS rescore
  45. 2026-08-16 05:17 UTCEG score recompute
  46. 2026-08-16 02:14 UTCEPSS rescore
  47. 2026-08-15 04:47 UTCEG score recompute
  48. 2026-08-15 01:30 UTCEPSS rescore
  49. 2026-08-14 15:39 UTCEG score recompute▲ 8.40
  50. 2026-08-14 15:38 UTCMITRE cvelistV5CVSS v3 → 8.4 · severity → HIGH
  51. 2026-08-13 22:25 UTCNVD update
  52. 2026-08-13 22:09 UTCEG score recompute
  53. 2026-08-13 22:09 UTCMITRE cvelistV5first tracked

Related CVEs(same vendor + 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 September 3, 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 98.7% 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

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