Fix transparency log tile verification bypass in golang.org/x/mod/sumdb/tlog
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
- GO-2026-6179
- openSUSE-SU-2026:11516-1
- openSUSE-SU-2026:11517-1
- openSUSE-SU-2026:11536-1
- openSUSE-SU-2026:11575-1
- openSUSE-SU-2026:21592-1
- openSUSE-SU-2026:21593-1
- openSUSE-SU-2026:21696-1
- openSUSE-SU-2026:21705-1
- openSUSE-SU-2026:21983-1
- SUSE-SU-2026:23300-1
- SUSE-SU-2026:23301-1
- SUSE-SU-2026:23573-1
- SUSE-SU-2026:23576-1
- SUSE-SU-2026:3640-1
- SUSE-SU-2026:3641-1
- SUSE-SU-2026:3799-1
- SUSE-SU-2026:3800-1
- SUSE-SU-2026:3815-1
- SUSE-SU-2026:3816-1
- Published
- Aug 13, 2026
- Updated
- Sep 3, 2026
- EPSS
- 0.1% · 3th percentile
- CWE
- CWE-347
Sign in to follow · You’ll be notified if a followed record enters KEV, gets an exploit or is updated.
Report tools
Action score
33
Monitor
Low priority for now.
- CVSS
- 33 / 40 · 8.4 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.1%
CISA SSVC decision
- Exploitation
- none
- Automatable
- no
- Technical impact
- total
Vulnrichment: CISA's decision-tree inputs.
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for the hundreds of thousands of vulnerabilities in the database; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpAffected systems
—
Versions reported by the vendor
Affected version ranges reported by the assigning authority (Go). Independent of NVD's CPE analysis and usually ahead of it.
Go toolchain cmd/go
- before 1.25.13affected · semver
- 1.26.0-0 and later · before 1.26.6affected · semver
- 1.27.0-0 and later · before 1.27.0-rc.3affected · semver
golang.org/x/mod golang.org/x/mod/sumdb/tlog
- before 0.40.0affected · semver
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | golang-1.19 | all versions | — |
| Debian:13 | golang-1.24 | all versions | — |
| Debian:14 | golang-1.25 | all versions | — |
| Debian:14 | golang-1.26 | before 1.26.6-1 | 1.26.6-1 |
| Debian:14 | golang-1.27 | before 1.27~rc3-1 | 1.27~rc3-1 |
| Go | golang.org/x/mod | before 0.40.0 | 0.40.0 |
| Go | toolchain | from 1.26.0-0 · before 1.26.6 | 1.26.6 |
| Go | toolchain | from 1.27.0-0 · before 1.27.0-rc.3 | 1.27.0-rc.3 |
| Go | toolchain | before 1.25.13 | 1.25.13 |
| openSUSE:Leap 16.0 | go1.25 | before 1.25.13-160000.1.1 | 1.25.13-160000.1.1 |
| openSUSE:Leap 16.0 | go1.25-openssl | before 1.25.14-160000.1.1 | 1.25.14-160000.1.1 |
| openSUSE:Leap 16.0 | go1.26 | before 1.26.6-160000.1.1 | 1.26.6-160000.1.1 |
| openSUSE:Leap 16.0 | go1.26-openssl | before 1.26.7-160000.1.1 | 1.26.7-160000.1.1 |
| openSUSE:Leap 16.0 | helm | before 4.3.0-160000.1.1 | 4.3.0-160000.1.1 |
| openSUSE:Tumbleweed | go1.25 | before 1.25.13-1.1 | 1.25.13-1.1 |
| openSUSE:Tumbleweed | go1.26 | before 1.26.6-1.1 | 1.26.6-1.1 |
| openSUSE:Tumbleweed | go1.27 | before 1.27rc3-1.1 | 1.27rc3-1.1 |
| openSUSE:Tumbleweed | helm | before 4.2.4-1.1 | 4.2.4-1.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | go1.25-openssl | before 1.25.14-150000.1.33.1 | 1.25.14-150000.1.33.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | go1.26-openssl | before 1.26.7-150000.1.18.1 | 1.26.7-150000.1.18.1 |
| SUSE:Linux Enterprise Module for Development Tools 15 SP7 | go1.25 | before 1.25.13-150000.1.50.1 | 1.25.13-150000.1.50.1 |
| SUSE:Linux Enterprise Module for Development Tools 15 SP7 | go1.25-openssl | before 1.25.14-150600.13.27.1 | 1.25.14-150600.13.27.1 |
| SUSE:Linux Enterprise Module for Development Tools 15 SP7 | go1.26 | before 1.26.6-150000.1.24.1 | 1.26.6-150000.1.24.1 |
| SUSE:Linux Enterprise Module for Development Tools 15 SP7 | go1.26-openssl | before 1.26.7-150600.13.15.1 | 1.26.7-150600.13.15.1 |
+5
Same product
go toolchain: all recordsOther highest-scoring records for the same primary product.
- CVE-2023-24531Output of "go env" does not sanitize values in cmd/go39Monitor
- CVE-2024-45340GOAUTH credential leak in cmd/go35Monitor
- CVE-2026-56864Ignore unrelated, unauthenticated hashes in Lookup in golang.org/x/mod/sumdb30Monitor
- CVE-2025-22867Arbitrary code execution during build on darwin in cmd/go30Monitor
- CVE-2024-24787Arbitrary code execution during build on Darwin in cmd/go25Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| Go toolchain cmd/go | 1.25.13 | Vendor (CNA) |
| Go toolchain cmd/go | 1.26.6 | Vendor (CNA) |
| Go toolchain cmd/go | 1.27.0-rc.3 | Vendor (CNA) |
| golang.org/x/mod golang.org/x/mod/sumdb/tlog | 0.40.0 | Vendor (CNA) |
| azl3 golang 1.26.7-1 on Azure Linux 3.0 | 1.26.6-1 · Release Notes | Microsoft (MSRC) |
| azl3 golang 1.27.0-1 on Azure Linux 3.0 | — | Microsoft (MSRC) |
| debian:golang-1.26 | 1.26.6-1 · Debian:14 | Package registry (OSV) |
| debian:golang-1.27 | 1.27~rc3-1 · Debian:14 | Package registry (OSV) |
| Go:golang.org/x/mod | 0.40.0 | Package registry (OSV) |
| Go:toolchain | 1.25.13 | Package registry (OSV) |
| Go:toolchain | 1.26.6 | Package registry (OSV) |
| Go:toolchain | 1.27.0-rc.3 | Package registry (OSV) |
| opensuse:go1.25 | 1.25.13-1.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| opensuse:go1.25-openssl | 1.25.14-160000.1.1 · openSUSE:Leap 16.0 | Package registry (OSV) |
| opensuse:go1.26 | 1.26.6-1.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| opensuse:go1.26-openssl | 1.26.7-160000.1.1 · openSUSE:Leap 16.0 | Package registry (OSV) |
| opensuse:go1.27 | 1.27rc3-1.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| opensuse:helm | 4.2.4-1.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| suse:go1.25 | 1.25.13-160000.1.1 · SUSE:Linux Enterprise Server 16.0 | Package registry (OSV) |
| suse:go1.25-openssl | 1.25.14-160000.1.1 · SUSE:Linux Enterprise Server 16.0 | Package registry (OSV) |
| suse:go1.26 | 1.26.6-160000.1.1 · SUSE:Linux Enterprise Server 16.0 | Package registry (OSV) |
| suse:go1.26-openssl | 1.26.7-160000.1.1 · SUSE:Linux Enterprise Server 16.0 | Package registry (OSV) |
| suse:go1.27 | 1.27.0-150000.1.6.1 · SUSE:Linux Enterprise Module for Development Tools 15 SP7 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
- CVE-2026-568640 days apartIgnore unrelated, unauthenticated hashes in Lookup in golang.org/x/mod/sumdb30Monitor
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Someone with local access to the system can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
- Attack vector
- Local
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-347 · Improper Verification of Cryptographic SignatureCVSS vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
nvd-secondary
Root cause
The verifier takes the algorithm to verify with from the token’s own header. Untrusted data ends up deciding its own verification rule.
The bug in code
The whole CWE-347 classA representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.
Vulnerable
const claims = jwt.verify(token, publicKey);Fixed
const claims = jwt.verify(token, publicKey, { algorithms: ["RS256"], issuer: "https://id.example.com", audience: "portal",});Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
ATT&CK techniques
—
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- go.dev/cl/814960
- go.dev/cl/815020
- go.dev/issue/80744
- groups.google.com/g/golang-announce/c/94pEornpRlI
- pkg.go.dev/vuln/GO-2026-6179
Vendor advisories and official records. Exploit/PoC links are deliberately left out.