Is CVE-2026-78667 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-78667 being exploited in the wild.

How severe is CVE-2026-78667?

High severity, with a CVSS score of 7.5, published 8 October 2026.

Which products and versions are affected?

go (Go) Go 1.27 and earlier; stdlib (Go) SEMVER:introduced=0,fixed=1.26.9,introduced=1.27.0-0,fixed=1.27.2.

How is CVE-2026-78667 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-78667?

Check whether you run go (Go) or stdlib (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.

CVE-2026-78667: Go net/http denial of service in Range header parsing

CVE-2026-78667 · Severity: high · CVSS 7.5 · Published 2026-10-08

Go's HTTP server implementation could consume excessive CPU when processing HTTP requests with Range headers containing many ranges. An attacker could craft a malicious Range header to cause a denial of service against web applications and services built with Go, making them unresponsive to legitimate requests.

Technologies: go (Go), stdlib (Go). Vendors: Go.

Quick answers

Is CVE-2026-78667 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-78667 being exploited in the wild.
How severe is CVE-2026-78667?: High severity, with a CVSS score of 7.5, published 8 October 2026.
Which products and versions are affected?: go (Go) Go 1.27 and earlier; stdlib (Go) SEMVER:introduced=0,fixed=1.26.9,introduced=1.27.0-0,fixed=1.27.2.
Is there a fix for CVE-2026-78667?: Yes. stdlib (Go): upgrade to 1.27.2 or later. Until then: Set GODEBUG=httpservecontentmaxranges=<limit> to configure the maximum number of allowed ranges; setting it to 0 disables the limit entirely if a workaround is needed before upgrading. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-78667 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-78667?: Check whether you run go (Go) or stdlib (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 1.27.2 or later
```
go get stdlib@v1.27.2
```

Set GODEBUG=httpservecontentmaxranges=<limit> to configure the maximum number of allowed ranges; setting it to 0 disables the limit entirely if a workaround is needed before upgrading.

Technical details

The net/http package's FileServer, ServeContent, and ServeFile functions lack limits on the number of ranges parsed from HTTP Range headers. An attacker can send a Range header with hundreds of small ranges to trigger excessive CPU consumption during parsing. The fix introduces a limit of 200 ranges by default, configurable via the httpservecontentmaxranges GODEBUG setting.

Affected products

Go Go Go 1.27 and earlier

Identifiers

CVE-2026-78667
GO-2026-6609

Timeline

2026-10-08: disclosed

References

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