Critical Apache flaw: worth asking your hosting provider
A critical flaw () in the module of the Apache web server was fixed on Nov 11: it allows remote code without logging in. Affected versions are 2.4.55–2.4.70; the fix is in 2.4.71. A server is vulnerable only if Apache itself offers connections; if a or nginx sits in front of it, traffic to Apache is often plain HTTP/1.1. Updating WordPress, plugins or Wordfence won't fix this, because the flaw is in the layer below PHP. Distributions often the fix, so the version number alone doesn't tell you whether a server is affected. The flaw was first reported by Anthropic's OSS Scanner (Oct 26). Public crash-inducing test code already exists; no attacks in the wild are known yet. According to a web search, this is already the second critical mod_http2 flaw of 2026 (the first was CVE-2026-23918 in May).
h2/h2c from the Protocols line and restart Apache. Make a fresh backup of the files and the database first. 1. Check: whether your Apache is affected (2.4.55–2.4.70 with enabled).
apache2ctl -v ; apache2ctl -M | grep http2 # Debian/Ubuntu
httpd -v ; httpd -M | grep http2 # RHEL/AlmaLinux, macOS (Homebrew)
grep -Rn "^\s*Protocols" /etc/apache2/ /etc/httpd/ 2>/dev/nullIf the version is 2.4.71 or later, or there's no h2 on the Protocols line, there's nothing to do. Distribution packages may include the fix under an older version number: your vendor's advisory tells you.
2. Backup: the site's files and database (e.g. mysqldump), plus the Apache configuration (sudo cp -a /etc/apache2 /root/apache2.bak).
3. Do it – update:
sudo apt update && sudo apt install --only-upgrade apache2 # Debian/Ubuntu
sudo dnf upgrade httpd mod_http2 # RHEL/AlmaLinux
brew update && brew upgrade httpd # macOS (Homebrew)If no fixed package is available yet: remove h2 and h2c from the Protocols line (Protocols http/1.1), or on Debian sudo a2dismod http2, then:
sudo apachectl configtest && sudo systemctl restart apache2 # RHEL: httpd4. Verify: curl -sI --http2 https://yourdomain.com -o /dev/null -w '%{http_version}\n' – 1.1 means is off. If a sits in front, this measures the , not your server.
Roll back: copy the saved configuration back (or sudo a2enmod http2), then restart Apache.
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