RUSTSEC-2023-0034: Resource exhaustion vulnerability in h2 may lead to Denial of Service (DoS)

What to do

1. See which version you have: cargo tree -i h2 (it also shows which of your dependencies pulls it in).
2. Update within your version requirement: cargo update -p h2. If the fix is a newer major or minor than your requirement allows, raise it in Cargo.toml (for example h2 = "0.3.17") or update the dependency that pulls it in.
3. Check again with cargo audit, or paste your Cargo.lock into our Cargo.toml checker.

Details from the advisory

If an attacker is able to flood the network with pairs of HEADERS/RST_STREAM frames, such that the h2 application is not able to accept them faster than the bytes are received, the pending accept queue can grow in memory usage. Being able to do this consistently can result in excessive memory use, and eventually trigger Out Of Memory.

This flaw is corrected in hyperium/h2#668, which restricts remote reset stream count by default.

References

• Package: crates.io/crates/h2
• Advisory: rustsec.org/advisories/RUSTSEC-2023-0034.html
• Report: github.com/hyperium/hyper/issues/2877

From the RustSec Advisory Database (CC0-1.0) via the OSV export, downloaded Oct 24, 2026. Severity score computed from the published CVSS vector.

Other advisories for h2

• VulnerabilityRUSTSEC-2024-0003 · 2024-01-17Resource exhaustion vulnerability in h2 may lead to Denial of Service (DoS)
• VulnerabilityRUSTSEC-2024-0332 · 2024-04-03Degradation of service in h2 servers with CONTINUATION Flood
• VulnerabilityRUSTSEC-2026-0258 · 2026-08-17h2 unbounded empty DATA frames

Full security history of h2