dbcve.org
HTTP ServerWeb server / proxy · Apache

CVE-2023-45802

MEDIUM · 5.9 CVSS v3.1 Published 2023-10-23
Fix available
A fix is available. Upgrade to 2.4.58 or later.
See remediation →
68/100
Remediation priority · Elevated
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
When a HTTP/2 stream was reset (RST frame) by a client, there was a time window were the request's memory resources were not reclaimed immediately. Instead, de-allocation was deferred to connection close. A client could send new requests and resets, keeping the connection busy and open and causing the memory footprint to keep on growing. On connection close, all resources were reclaimed, but the process might run out of memory before that. This was found by the reporter during testing of CVE-2023-44487 (HTTP/2 Rapid Reset Exploit) with their own test client. During "normal" HTTP/2 use, the probability to hit this bug is very low. The kept memory would not become noticeable before the connection closes or times out. Users are recommended to upgrade to version 2.4.58, which fixes the issue.

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

When HTTP/2 streams are reset via RST frames, the server defers memory deallocation until connection close rather than releasing resources immediately. A client can exploit this by sending repeated requests and resets, causing memory to accumulate without bounds until the connection closes or times out, potentially leading to memory exhaustion.

MitigationUpgrade Apache HTTP Server to version 2.4.58 or later to resolve the deferred memory deallocation issue.

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:>= 2.4.17, < 2.4.58
FedoraOperating system
Affected:= 37= 38= 39
Debian LinuxOperating system
Affected:= 10.0

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
High
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:H/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. Verify Apache HTTP Server is installed
    Run `httpd -v` (or `apache2 -v` on Debian/Ubuntu) to retrieve the server version
    Affected if No Apache server is installed, then this CVE does not apply to your environment
  2. Compare installed version to affected range
    Check if the version is >= 2.4.17 and < 2.4.58. The command output shows the version number in the format 'Server version: Apache/2.4.x'
    Affected if The installed version falls within >= 2.4.17 and < 2.4.58, indicating a potentially vulnerable version
  3. Confirm HTTP/2 module is loaded
    Run `httpd -M` or `apache2ctl -M` and look for 'http2' or 'mod_http2' in the loaded modules list
    Affected if The mod_http2 module is not loaded, the vulnerability cannot be triggered since it only affects HTTP/2 connections
  4. Check if HTTP/2 is enabled in configuration
    Inspect your Apache configuration files (e.g., httpd.conf, ssl.conf, or included config files) for 'Protocols h2 h2c' or 'SSLProtocol' directives that enable HTTP/2
    Affected if HTTP/2 protocol is explicitly enabled in the configuration, making the environment vulnerable to the memory exhaustion issue when RST frames are received

Your environment is affected if you have Apache HTTP Server version 2.4.17 through 2.4.57 with mod_http2 loaded and HTTP/2 protocol enabled in your configuration.

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 2.4.58 or later
Fixed in 2.4.58
Interim mitigation

Upgrade Apache HTTP Server to version 2.4.58 or later to resolve the deferred memory deallocation issue.

Recommended fix High confidence

Apache HTTP Server 2.4.58

  1. Check current Apache HTTP Server version (e.g., httpd -v or apache2 -v)
  2. Stop the Apache service before upgrading (e.g., systemctl stop httpd or systemctl stop apache2)
  3. Update the Apache package to version 2.4.58 using the system's package manager
  4. Verify the installed version matches 2.4.58
  5. Restart the Apache service (e.g., systemctl start httpd or systemctl start apache2)
Caveat Moderate risk - review module compatibility and configuration settings after upgrade, especially for HTTP/2 configurations

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
  • Implementation3.0 h
  • Testing2.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,420
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,272.

Scan for this in your stack

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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-2023-45802 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