dbcve.org
HTTP ServerWeb server / proxy · Apache

CVE-2022-37436

MEDIUM · 5.3 CVSS v3.1 Published 2023-01-17
Fix available
A fix is available. Upgrade to 2.4.55 or later.
See remediation →
62/100
Remediation priority · Elevated
High EPSS 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
Prior to Apache HTTP Server 2.4.55, a malicious backend can cause the response headers to be truncated early, resulting in some headers being incorporated into the response body. If the later headers have any security purpose, they will not be interpreted by the client.

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

In Apache HTTP Server prior to 2.4.55, a malicious backend server in a reverse proxy configuration can trigger early truncation of HTTP response headers. This causes some headers to be incorrectly included in the response body instead of being processed as headers. Security-relevant headers (such as CSP, HSTS, or authentication headers) that appear after the truncation point will be ignored by the client, potentially enabling response smuggling or security control bypass.

MitigationUpgrade Apache HTTP Server to version 2.4.55 or later. If immediate patching is not possible, audit all backend servers and proxy configurations to ensure no malicious servers can manipulate header responses.

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:< 2.4.55

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
Low
Availability
None

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

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 display the server version. Alternatively, check the server response header via 'curl -I <your-server>' or inspect the 'Server' field in HTTP responses.
    Affected if The installed version is lower than 2.4.55 (e.g., 2.4.54, 2.4.53, etc.)
  2. Verify mod_proxy is enabled
    Check for loaded proxy modules by running 'httpd -M 2>/dev/null | grep proxy' or 'apache2ctl -M 2>/dev/null | grep proxy'. Also inspect the Apache config files (httpd.conf, apache2.conf) for 'LoadModule proxy_module' and related proxy modules.
    Affected if mod_proxy or any reverse proxy module is loaded and active in the configuration
  3. Identify active reverse proxy configurations
    Search configuration files (httpd.conf, included .conf files in conf.d or sites-enabled) for 'ProxyPass', 'ProxyPassReverse', 'ProxyRequests', or 'RewriteRule' with the [P] flag. Run: 'grep -r "ProxyPass\|ProxyPassReverse" /etc/apache2/ /etc/httpd/' to locate proxy directives.
    Affected if Any ProxyPass or ProxyPassReverse directives are configured, indicating reverse proxy to backend servers
  4. Inspect backend server trust model
    Review the proxy configuration to identify defined backend servers. Look for the target URLs in ProxyPass directives (e.g., 'ProxyPass / http://backend:8080/'). Identify whether these backends are internally controlled or potentially untrusted external servers.
    Affected if The reverse proxy points to backend servers that are not fully trusted or are externally accessible without proper sanitization controls

You are affected if Apache HTTP Server version is below 2.4.55 AND the server is configured as a reverse proxy (with mod_proxy) pointing to backend servers.

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 2.4.55 or later
Fixed in 2.4.55
Interim mitigation

Upgrade Apache HTTP Server to version 2.4.55 or later. If immediate patching is not possible, audit all backend servers and proxy configurations to ensure no malicious servers can manipulate header responses.

Recommended fix Moderate confidence

Apache HTTP Server 2.4.55

  1. Identify the current Apache HTTP Server version using 'httpd -v' or 'apache2 -v'
  2. Stop the Apache HTTP Server service using 'systemctl stop apache2' (Debian/Ubuntu) or 'systemctl stop httpd' (RHEL/CentOS)
  3. Update the package repository and upgrade Apache HTTP Server to version 2.4.55 or later
  4. For Debian/Ubuntu: apt update && apt install apache2
  5. For RHEL/CentOS: yum update httpd
  6. Verify the new version is installed using 'httpd -v' or 'apache2 -v'
  7. Start the Apache HTTP Server service using 'systemctl start apache2' or 'systemctl start httpd'
  8. Ensure the service is enabled to start on boot using 'systemctl enable apache2' or 'systemctl enable httpd'

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

Fix this in HTTP Server Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,040
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,664.

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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-2022-37436 in production — separate from our analysis above.

No notes yet

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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