html: impose open element stack size limit

The HTML specification contains a number of algorithms which are
quadratic in complexity by design. Instead of adding complicated
workarounds to prevent these cases from becoming extremely expensive in
pathological cases, we impose a limit of 512 to the size of the stack of
open elements. It is extremely unlikely that non-adversarial HTML
documents will ever hit this limit (but if we see cases of this, we may
want to make the limit configurable via a ParseOption).

Thanks to Guido Vranken and Jakub Ciolek for both independently
reporting this issue.

Fixes CVE-2025-47911
Fixes golang/go#75682

Change-Id: I890517b189af4ffbf427d25d3fde7ad7ec3509ad
Reviewed-on: https://go-review.googlesource.com/c/net/+/709876
Reviewed-by: Damien Neil <dneil@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
3 files changed
tree: 858913fd630d3606f1a59de6b9ece80f8bf751df
  1. bpf/
  2. context/
  3. dict/
  4. dns/
  5. html/
  6. http/
  7. http2/
  8. icmp/
  9. idna/
  10. internal/
  11. ipv4/
  12. ipv6/
  13. lif/
  14. nettest/
  15. netutil/
  16. proxy/
  17. publicsuffix/
  18. quic/
  19. route/
  20. trace/
  21. webdav/
  22. websocket/
  23. xsrftoken/
  24. .gitattributes
  25. .gitignore
  26. codereview.cfg
  27. CONTRIBUTING.md
  28. go.mod
  29. go.sum
  30. LICENSE
  31. PATENTS
  32. README.md
README.md

Go Networking

Go Reference

This repository holds supplementary Go networking packages.

Report Issues / Send Patches

This repository uses Gerrit for code changes. To learn how to submit changes to this repository, see https://go.dev/doc/contribute.

The git repository is https://go.googlesource.com/net.

The main issue tracker for the net repository is located at https://go.dev/issues. Prefix your issue with “x/net:” in the subject line, so it is easy to find.