dbcve.org
HTTP ServerWeb server / proxy · Apache

CVE-2025-49630

HIGH · 7.5 CVSS v3.1 Published 2025-07-10
Fix available
A fix is available. Upgrade to 2.4.64 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In certain proxy configurations, a denial of service attack against Apache HTTP Server versions 2.4.26 through to 2.4.63 can be triggered by untrusted clients causing an assertion in mod_proxy_http2. Configurations affected are a reverse proxy is configured for an HTTP/2 backend, with ProxyPreserveHost set to "on".

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A denial of service vulnerability exists in Apache HTTP Server's mod_proxy_http2 module. When configured as a reverse proxy with an HTTP/2 backend and ProxyPreserveHost enabled, untrusted clients can trigger an assertion failure causing the server to crash.

MitigationDisable ProxyPreserveHost in affected reverse proxy configurations, or upgrade to Apache HTTP Server version 2.4.64 or later once available.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
HTTP ServerWeb server / proxy
Affected:>= 2.4.26, < 2.4.64

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check Apache HTTP Server version
    Run 'httpd -v' or 'apache2 -v' to get the installed version number
    Affected if Version is >= 2.4.26 and < 2.4.64
  2. Verify mod_proxy_http2 is loaded
    Check for 'LoadModule proxy_http2_module' in httpd.conf or run 'httpd -M' to list loaded modules
    Affected if Module is loaded and Apache version is in the affected range
  3. Confirm ProxyPreserveHost is enabled
    Search configuration files for 'ProxyPreserveHost On' directive
    Affected if ProxyPreserveHost is set to On and mod_proxy_http2 is in use
  4. Identify reverse proxy configurations with HTTP/2 backends
    Search config for 'ProxyPass' or 'ProxyPassMatch' directives combined with 'Http2' protocol setting or h2 backend URLs
    Affected if A reverse proxy rule points to an HTTP/2 backend and ProxyPreserveHost is enabled

User is affected if Apache version is between 2.4.26 and 2.4.63, mod_proxy_http2 is loaded, ProxyPreserveHost is On, and the server acts as a reverse proxy to an HTTP/2 backend.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 2.4.64 or later
Fixed in 2.4.64
Interim mitigation

Disable ProxyPreserveHost in affected reverse proxy configurations, or upgrade to Apache HTTP Server version 2.4.64 or later once available.

Recommended fix High confidence

2.4.64 or later

  1. 1. Identify the current Apache HTTP Server version by running 'apache2 -v' or 'httpd -v'
  2. 2. Backup all Apache configuration files (typically in /etc/apache2 or /etc/httpd) and any custom modules
  3. 3. Update your system's package repository to ensure you have access to the latest packages
  4. 4. Upgrade Apache HTTP Server using your system's package manager (e.g., 'apt-get update && apt-get install apache2' for Debian/Ubuntu, or 'yum update httpd' for RHEL/CentOS)
  5. 5. Verify the upgrade was successful by checking the version (should show 2.4.64 or later)
  6. 6. Restart the Apache service (e.g., 'systemctl restart apache2' or 'systemctl restart httpd')
  7. 7. Test that the reverse proxy configuration still functions correctly with your HTTP/2 backend
Caveat Minor: Review ProxyPreserveHost behavior changes between 2.4.26-2.4.63 if using this directive; also review mod_proxy_http2 module changes in release notes

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in HTTP Server Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,984.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-49630 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data