CVE-2023-50247 h2o QUIC state exhaustion DoS

What is CVE-2023-50247?

CVE-2023-50247 is a low-severity denial of service vulnerability in h2o, published on 12 Dec 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. The QUIC stack (quicly), as used by H2O up to commit 43f86e5 (in version 2.3.0-beta and prior), is susceptible to a state exhaustion attack. When H2O is serving HTTP/3, a remote attacker can exploit this vulnerability to progressively increase the memory retained by the QUIC stack. This can eventually cause H2O to abort due to memory exhaustion. The vulnerability has been resolved in commit d67e81d03be12a9d53dc8271af6530f40164cd35. HTTP/1 and HTTP/2 are not affected by this vulnerability as they do not use QUIC. Administrators looking to mitigate this issue without upgrading can disable HTTP/3 support.

Weakness: CWE-770

Which versions are affected by CVE-2023-50247?

It affects 1 product.

Products include Dena H2o.

How do I fix CVE-2023-50247?

No fix has been published for CVE-2023-50247 yet. Limit exposure of the affected software until one is available.

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-2023-50247 being exploited?

There is no known exploitation of CVE-2023-50247 in the wild and no public exploit code.

Other vulnerabilities in h2o

• CVE-2018-0608 Memory corruption in H2O Critical 9.8
• CVE-2016-7835 Use after free in H2O Critical 9.1
• CVE-2023-30847 H2O vulnerable to read from uninitialized pointer in the reverse proxy handler High 8.2
• CVE-2017-10868 Denial of service in H2O High 7.5
• CVE-2017-10869 Memory corruption in H2O High 7.5

Sources

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

Also known as GHSA-2ch5-p59c-7mv6.