Answer in brief
CVE-2026-56853 records a Unknown severity vulnerability in Apply ReadHeaderTimeout when doing unencrypted HTTP/2 check in net/http. The current sources do not mark it as known exploited. The current feed maps Go standard library/net/http (generic), stdlib (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 standard library/net/http (generic), stdlib (go). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Go standard library/net/httpgeneric | >=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 |
| stdlibgo | >=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
When a server is configured to support unencrypted HTTP/2, it reads a few bytes from each new connection to see if they contain the HTTP/2 client preface. ReadHeaderTimeout is unexpectedly not being applied when doing this.
Quoted source text, attributed separately from HOL analysis.
Answer in brief
CVE-2026-56853 records a Unknown severity vulnerability in Apply ReadHeaderTimeout when doing unencrypted HTTP/2 check in net/http. The current sources do not mark it as known exploited. The current feed maps Go standard library/net/http (generic), stdlib (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 standard library/net/http (generic), stdlib (go). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Go standard library/net/httpgeneric | >=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 |
| stdlibgo | >=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
When a server is configured to support unencrypted HTTP/2, it reads a few bytes from each new connection to see if they contain the HTTP/2 client preface. ReadHeaderTimeout is unexpectedly not being applied when doing this.
Quoted source text, attributed separately from HOL analysis.