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docs(known-issues): document early blocking#222

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fzipi wants to merge 4 commits intomainfrom
chore/add-early-blocking-docs
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docs(known-issues): document early blocking#222
fzipi wants to merge 4 commits intomainfrom
chore/add-early-blocking-docs

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@fzipi fzipi commented Jun 19, 2025

what

  • document early blocking problems as known issues

Fixes #221

Signed-off-by: Felipe Zipitria <felipe.zipitria@owasp.org>
@fzipi fzipi requested a review from a team June 19, 2025 14:14
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Co-authored-by: Xhoenix <86168235+Xhoenix@users.noreply.github.com>
Comment on lines 18 to 19
> **Enable early execution of phase 1 rules**
> By default, ModSecurity does **not** activate this flag. Phase 1 rules run **after** the request headers are fully read. This flag allows certain phase 1 rules to trigger *earlier*, potentially before the full header set is available.
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I think this is the wrong way around. @airween? Didn't the issue say they used --disable-request-early?

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Yes, @theseion is right. I think we should suggest don't use --disable-request-early flag.

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Ugh. Is it just the name, or the behavior completely changes? Can you point me to the docs?

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I just found this one:

Starting with ModSecurity 2.7.0 there are a few important configuration options

  1. --enable-request-early - On ModSecurity 2.6 phase one has been moved to phase 2 hook, if you want to play around it use this option.

But in configure.ac, the logic is in opposite direction:

  if test "$enableval" != "no"; then
    request_early="-DREQUEST_EARLY"
    MODSEC_EXTRA_CFLAGS="$MODSEC_EXTRA_CFLAGS $request_early"
  else
    request_early=
  fi
],
[
  request_early='-DREQUEST_EARLY'

The logic:

  • if the user passes this option, and the value is not no (which equals with --disable-request-early, then feature will be turned ON
  • if the user does not pass this option, then the build script assumes it's necessary and will be turned ON

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Any updates on this?

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Ping @coreruleset/core-developers

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@Xhoenix Did my best. Can you re-review?

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@Xhoenix Xhoenix Feb 7, 2026

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The ModSec Docs conflict with this --disable-request-early flag, and suggest --enable-request-early https://github.com/owasp-modsecurity/ModSecurity/wiki/Reference-Manual-%28v2.x%29#start-apache-httpd. Maybe the Docs need to be updated.

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Pull request overview

This PR documents the --enable-request-early ModSecurity compilation flag in the CRS known issues section, addressing issue #221. The documentation explains why this flag should remain disabled by default and describes the risks associated with enabling it. Additionally, the PR reorganizes the existing known issues with improved formatting using emojis for better visual structure.

Changes:

  • Added comprehensive documentation for ModSecurity's --enable-request-early flag including motivation, technical details, risks, and recommendations
  • Reorganized existing known issues into categorized sections (Apache, ModSecurity, Debian, CRS + ModSecurity, libmodsecurity3)
  • Enhanced visual structure with emoji icons for improved readability

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

fzipi and others added 2 commits February 6, 2026 19:02
Signed-off-by: Felipe Zipitria <felipe.zipitria@owasp.org>
@fzipi fzipi requested review from Xhoenix, airween and theseion February 6, 2026 22:23
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Add documentation for the --enable-request-early compilation flag

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