CVE-2023-50247: h2o QUIC state exhaustion DoS
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.
Affected Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2023-50247?
CVE-2023-50247 is classified as a high-severity vulnerability due to its potential for a state exhaustion attack.
How do I fix CVE-2023-50247?
To fix CVE-2023-50247, upgrade to H2O version 2.3.0-beta3 or later.
What versions of H2O are affected by CVE-2023-50247?
CVE-2023-50247 affects H2O versions up to and including 2.2.6 and both beta versions 2.3.0-beta1 and 2.3.0-beta2.
What type of attack does CVE-2023-50247 enable?
CVE-2023-50247 enables a state exhaustion attack against the QUIC stack when H2O is serving HTTP/3.
Who can exploit CVE-2023-50247?
CVE-2023-50247 can be exploited by remote attackers targeting servers running vulnerable versions of H2O.