CVE-2026-56865
Fix transparency log tile verification bypass in golang.org/x/mod/sumdb/tlog
HIGH 8.4
At a glance
- Source
- NVD
- EPSS
- EPSS 0.13 % · percentile 3 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- Go
- NVD status
- Awaiting Analysis
Description
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
Weaknesses (CWE)
- CWE-347 — Improper Verification of Cryptographic Signature
References
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 3.1 | HIGH 8.4 | CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H | CISA-ADP |
| CVSS 3.1 | HIGH 8.4 | CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H | NVD · 134c704f-9b21-4f2e-91b3-4a467353bcc0 (Secondary) |
Advisories
- GO-2026-6179 — Fix transparency log tile verification bypass in golang.org/x/mod/sumdb/tlog
European references
- ENISA EUVD · EUVD-2026-58513
- GCVE · GCVE-0-2026-56865
CERT-FR advisories
- CERTFR-2026-AVI-1385 — Multiples vulnérabilités dans les produits VMware · cert.ssi.gouv.fr
- CERTFR-2026-AVI-1249 — Multiples vulnérabilités dans les produits VMware · cert.ssi.gouv.fr
- CERTFR-2026-AVI-1125 — Multiples vulnérabilités dans les produits VMware · cert.ssi.gouv.fr
Affected products
| Product | Versions |
|---|---|
| Go toolchain · cmd/go | affected 0 < 1.25.13 ; affected 1.26.0-0 < 1.26.6 ; affected 1.27.0-0 < 1.27.0-rc.3 |
| golang.org/x/mod · golang.org/x/mod/sumdb/tlog | affected 0 < 0.40.0 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| CERT-FR (ANSSI) | Licence Ouverte / Etalab 2.0 |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |