CVE-2023-45802 Apache HTTP Server: HTTP/2 stream memory not reclaimed right away on RST

What is CVE-2023-45802?

CVE-2023-45802 is a medium-severity denial of service vulnerability in Apache Http Server, published on 23 Oct 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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.

Weakness: CWE-404

Which versions are affected by CVE-2023-45802?

1 open source package ship an affected version, including apache. It affects 3 products.

Products include Apache Http Server, Debian Debian Linux, Fedoraproject Fedora.

How do I fix CVE-2023-45802?

Upgrade apache to 2.4.58 or later.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2023-45802 being exploited?

There is no known exploitation of CVE-2023-45802 in the wild and no public exploit code.

Public exploit code: 1 proofs of concept on GitHub.

Other vulnerabilities in Apache Http Server

• CVE-2021-42013 Apache HTTP Server Path Traversal Exploited Critical 9.8
• CVE-2024-38475 Apache HTTP Server Improper Escaping of Output Exploited Critical 9.1
• CVE-2021-40438 Apache HTTP Server-Side Request Forgery (SSRF) Exploited Critical 9.0
• CVE-2019-0211 Apache HTTP Server Privilege Escalation Exploited High 7.8
• CVE-2021-41773 Apache HTTP Server Path Traversal Exploited High 7.5

All Apache Http Server vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as ALPINE-CVE-2023-45802, AZL-31611, AZL-43531, AZL-45147, BELL-CVE-2023-45802, BIT-apache-2023-45802 and 10 more.