# CVE-2026-97054: Go HTTP/1 server race condition in MaxBytesReader header handling

Source: https://junglewise.ai/threats/cve-2026-97054-for-http-1-servers-when-maxbytesreader-s-limit-is-exceeded  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-11. Updated: 2026-11-11  
License: CC BY 4.0 with a link back

CVE-2026-97054 · Severity: info · Published 2026-11-11

Go's HTTP/1 server framework automatically sets a "Connection: close" header when a request body exceeds size limits, but does so without synchronization. If a server handler concurrently reads the request body and writes response headers, a race condition can cause the server to crash with a runtime panic, resulting in denial of service.

Technologies: [stdlib (Go)](https://junglewise.ai/threats/technologies/go-stdlib), [Google Go](https://junglewise.ai/threats/technologies/google-go). Vendors: [Go](https://junglewise.ai/threats/vendors/go), [Google](https://junglewise.ai/threats/vendors/google).

## Quick answers

**Is CVE-2026-97054 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-97054 being exploited in the wild.

**How severe is CVE-2026-97054?** Informational severity, published 11 November 2026.

**Which products and versions are affected?** stdlib (Go) SEMVER:introduced=0,fixed=1.26.11,introduced=1.27.0-0,fixed=1.27.4; Google Go <UNKNOWN>.

**Is there a fix for CVE-2026-97054?** Yes. stdlib (Go): upgrade to 1.27.4 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-97054 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-97054?** Check whether you run stdlib (Go) or Google Go at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- stdlib (Go): upgrade to 1.27.4 or later

  ```sh
  go get stdlib@v1.27.4
  ```


## Technical details

A race condition exists in Go's HTTP/1 server implementation when MaxBytesReader or MaxBytesHandler exceeds its limit: the framework sets the "Connection: close" header unsynchronized, racing with user code that sets headers in the handler. An attacker sends a request with a body larger than the configured limit while the handler concurrently writes response headers, triggering a panic that crashes the server process.

## Affected products

- Google Go <UNKNOWN>

## Identifiers

- CVE-2026-97054
- GO-2026-6859

## Timeline

- 2026-11-11: disclosed

## References

- [https://pkg.go.dev/](https://pkg.go.dev/)
- [https://go.dev/cl/862185](https://go.dev/cl/862185)

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