# CVE-2026-25680: Go net/html denial of service in HTML tree construction

Source: https://junglewise.ai/threats/cve-2026-25680-go-net-html-denial-of-service-in-html-tree-construction  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-22. Updated: 2026-07-01  
License: CC BY 4.0 with a link back

CVE-2026-25680 · Severity: medium · CVSS 6.5 · Published 2026-05-22

A vulnerability in the Go programming language's standard networking library could allow an attacker to crash or slow down applications that process web content. By providing a specially crafted HTML file, an attacker can force the system to consume excessive processor resources, leading to a denial of service. This affects any Go-based service or tool that uses the affected library to parse HTML from external sources.

Technologies: [golang.org/x/net (Go)](https://junglewise.ai/threats/technologies/golang-org-x-net), [net/html (Go)](https://junglewise.ai/threats/technologies/net-html). Vendors: [Go](https://junglewise.ai/threats/vendors/go).

## Quick answers

**Is CVE-2026-25680 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-25680 being exploited in the wild.

**How severe is CVE-2026-25680?** Medium severity, with a CVSS score of 6.5, published 22 May 2026.

**Which products and versions are affected?** golang.org/x/net (Go) < 0.55.0, SEMVER:introduced=0,fixed=0.55.0; net/html (Go) before v0.55.0.

**Is there a fix for CVE-2026-25680?** Yes. golang.org/x/net (Go): upgrade to 0.55.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-25680 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-25680?** Check whether you run golang.org/x/net (Go) or net/html (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

- golang.org/x/net (Go): upgrade to 0.55.0 or later

  ```sh
  go get golang.org/x/net@v0.55.0
  ```


## Technical details

A vulnerability in the Go Net (`golang.org/x/net`) HTML parser allows for uncontrolled resource consumption (CWE-400). When parsing arbitrary, malicious HTML input, the parser can be forced to consume excessive CPU time. The attack vector is network-based and requires no special privileges, though it is categorized as requiring user interaction (e.g., a user or service processing a malicious file). This can result in a sustained denial of service for the affected application. The issue is resolved in version 0.55.0 of the library.

## Affected products

- Go x/net < 0.55.0

## Identifiers

- CVE-2026-25680
- GHSA-5cv4-jp36-h3mw
- GO-2026-5028

## Timeline

- 2026-05-22: disclosed: NVD publication date
- 2026-05-26: advisory: GitHub Advisory published
- 2026-07-01: patched: GitHub Advisory reviewed and updated with patch information

## References

- [https://api.github.com/users/joepurdy](https://api.github.com/users/joepurdy)
- [https://github.com/joepurdy](https://github.com/joepurdy)
- [https://api.github.com/users/joepurdy/gists%7B/gist_id%7D](https://api.github.com/users/joepurdy/gists%7B/gist_id%7D)
- [https://api.github.com/users/joepurdy/repos](https://api.github.com/users/joepurdy/repos)
- [https://avatars.githubusercontent.com/u/6409227?v=4](https://avatars.githubusercontent.com/u/6409227?v=4)
- [https://api.github.com/users/joepurdy/events%7B/privacy%7D](https://api.github.com/users/joepurdy/events%7B/privacy%7D)

## Related threats

- [Go html parser namespace handling in childTextNodesAreLiteral](https://junglewise.ai/threats/cve-2026-97045-in-childtextnodesareliteral-walking-up-the-tree-previously)
- [Go HTML parser quadratic time complexity in text node coalescing](https://junglewise.ai/threats/cve-2026-78661-when-coalescing-adjacent-text-nodes-in-addtext-and-fosterparent)
- [Google Go x/net denial of service in dnsmessage parsing](https://junglewise.ai/threats/cve-2026-46600-google-go-x-net-denial-of-service-in-dnsmessage-parsing)
- [Golang net/html Cross-Site Scripting via incorrect namespaced element parsing](https://junglewise.ai/threats/cve-2026-42506-golang-net-html-cross-site-scripting-via-incorrect-namespaced)
- [Google Go x/net/html XSS via incorrect foreign content parsing](https://junglewise.ai/threats/cve-2026-42502-google-go-x-net-html-xss-via-incorrect-foreign-content-parsing)