CVE-2026-56865

HIGHPre-NVD 8.48.4
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

This high-severity CVE scores 8.4 under CISA-ADP (Vulnrichment) CVSS v3.1 (NVD's own analysis pending). EPSS exploit probability: 0.1% (2nd percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from CISA-ADP (Vulnrichment) CVSS v3.1
Sources: CISA-ADP (Vulnrichment) CVSS v3.1, EPSS
Trending — 3 sources updated this week

Also known asEUVD-2026-58513 (ENISA EUVD)Source: ENISA EUVD

8.4EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.1%CVSS: 8.4Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

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
8.4HIGHmedium confidence
EG Risk
38
EG Risk 38/100

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)
Severity84% × 45%
Impact severity (EG Severity): CVSS 8.4 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 low or medium mission impact; Track* at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (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 (8.4): severity, escalated by confirmed exploitation. This CVE's 8.4 is its impact severity (EG Severity), not escalated.

EG Severity
8.4 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.CISA-ADP (Vulnrichment) CVSS v3.1 · CVSS v3.1
EG Likelihood
0.1% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-31). 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 low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 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 low or medium mission impact; Track* at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (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)14 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 total (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

August 13, 2026

Last Modified

September 3, 2026

Advisory Details (5)

Auto-updated Aug 14, 2026
Patch available.
Web page

GO-2026-6179 - Go Packages

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

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

https://go.dev/issue/80744

Vendor Advisories for CVE-2026-56865(3)

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

Patch Availability(3)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntugolang-1.22-src (1.22.2-2ubuntu0.5) @ noble2026-11-01ubuntu
redhatcluster-observability-operator/cluster-observability-rhel9-operator:17908545992026-10-01redhat
redhatadvanced-cluster-security/rhacs-rhel9-operator:17894113202026-09-15redhat

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

(7 across 4 ecosystems)
Debian:14(3)
PackageVulnerable rangeFix by version rangeDependents
golang-1.251.25.0-1 ... 1.25.9-1 (20 versions)
  • every version on: no fix on record
—
golang-1.261.26.0-1 ... 1.26~rc3-2 (16 versions)
  • every version up to 1.26.6-1: fixed in 1.26.6-1
—
golang-1.271.27~rc1-1, 1.27~rc2-1
  • every version up to 1.27~rc3-1: fixed in 1.27~rc3-1
—
Go(2)
PackageVulnerable rangeFix by version rangeDependents
golang.org/x/mod—
  • every version up to 0.40.0: fixed in 0.40.0
—
toolchain—
  • every version up to 1.25.13: fixed in 1.25.13
  • 1.26.0-0 up to 1.26.6: fixed in 1.26.6
  • 1.27.0-0 up to 1.27.0-rc.3: fixed in 1.27.0-rc.3
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
golang-1.191.19.10-1 ... 1.19.9-1 (12 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
golang-1.241.24.12-1 ... 1.24.9-1 (10 versions)
  • every version on: no fix on record
—

Weakness Classification(1)

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

Additional Vendor Advisories

(1)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 9× in last 7d / 50× 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 167 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 67 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

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

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

Frequently asked(5)

What is CVE-2026-56865?
CVE-2026-56865 is a high-severity vulnerability; its CVE record was 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 the CVE record for CVE-2026-56865 published?
The CVE record for CVE-2026-56865 was published on August 13, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of September 3, 2026; the record at its source may have been updated since.
Is CVE-2026-56865 actively exploited?
CVE-2026-56865 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-2026-56865?
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?
A fix for CVE-2026-56865 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-56865 are linked in the Vendor Advisories panel on this page.

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