Answer in brief
CVE-2026-56864 records a Unknown severity vulnerability in Ignore unrelated, unauthenticated hashes in Lookup in golang.org/x/mod/sumdb. The current sources do not mark it as known exploited. The current feed maps Go toolchain/cmd/go (generic), golang.org/x/mod/golang.org/x/mod/sumdb (generic), golang.org/x/mod (go), toolchain (go). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Go toolchain/cmd/go (generic), golang.org/x/mod/golang.org/x/mod/sumdb (generic), golang.org/x/mod (go), toolchain (go). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Go toolchain/cmd/gogeneric | >=0 <1.25.13 || >=1.26.0-0 <1.26.6 || >=1.27.0-0 <1.27.0-rc.3 | 1.25.13, 1.26.6, 1.27.0-rc.3 |
| golang.org/x/mod/golang.org/x/mod/sumdbgeneric | >=0 <0.40.0 | 0.40.0 |
| golang.org/x/modgo | >=0 <0.40.0 | 0.40.0 |
| toolchaingo | >=0 <1.25.13 >=1.26.0-0 <1.26.6 >=1.27.0-0 <1.27.0-rc.3 | 1.25.13, 1.26.6, 1.27.0-rc.3 |
Published upstream
Aug 13, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 13, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 13, 2026
A malicious GOSUMDB was capable of serving arbitrary module content not contained within the transparency log. This attack allows for a coordinating GOPROXY and GOSUMDB to serve a client malicious module content that cannot be detected by evaluating the transparency log. In order to determine if you have been affected: rm -r go.sum go.work.sum vendor/ && go mod tidy
Quoted source text, attributed separately from HOL analysis.
Answer in brief
CVE-2026-56864 records a Unknown severity vulnerability in Ignore unrelated, unauthenticated hashes in Lookup in golang.org/x/mod/sumdb. The current sources do not mark it as known exploited. The current feed maps Go toolchain/cmd/go (generic), golang.org/x/mod/golang.org/x/mod/sumdb (generic), golang.org/x/mod (go), toolchain (go). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Go toolchain/cmd/go (generic), golang.org/x/mod/golang.org/x/mod/sumdb (generic), golang.org/x/mod (go), toolchain (go). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Go toolchain/cmd/gogeneric | >=0 <1.25.13 || >=1.26.0-0 <1.26.6 || >=1.27.0-0 <1.27.0-rc.3 | 1.25.13, 1.26.6, 1.27.0-rc.3 |
| golang.org/x/mod/golang.org/x/mod/sumdbgeneric | >=0 <0.40.0 | 0.40.0 |
| golang.org/x/modgo | >=0 <0.40.0 | 0.40.0 |
| toolchaingo | >=0 <1.25.13 >=1.26.0-0 <1.26.6 >=1.27.0-0 <1.27.0-rc.3 | 1.25.13, 1.26.6, 1.27.0-rc.3 |
Published upstream
Aug 13, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 13, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 13, 2026
A malicious GOSUMDB was capable of serving arbitrary module content not contained within the transparency log. This attack allows for a coordinating GOPROXY and GOSUMDB to serve a client malicious module content that cannot be detected by evaluating the transparency log. In order to determine if you have been affected: rm -r go.sum go.work.sum vendor/ && go mod tidy
Quoted source text, attributed separately from HOL analysis.