CVE-2026-10740: Excessive memory allocation in s2n-quic
s2n-quic is a Rust implementation of the QUIC protocol. An unauthenticated user can attempt to exhaust server memory on an s2n-quic endpoint by sending crafted CRYPTO frames with high offsets. The buffer used for processing CRYPTO frames does not enforce a maximum size. In the worst case, a single 1200-byte packet can cause approximately 9.4 MB of allocation. By repeatedly sending such packets, the resulting memory pressure could cause denial of service. No valid handshake is required.
Impacted versions: <= v1.81.0
Patches This issue has been addressed in s2n-quic version v1.82.0. We recommend upgrading to the latest version and ensuring any forked or derivative code is patched to incorporate the new fixes.
Workarounds There is no workaround that fully mitigates this issue. Upgrading to the patched version is the recommended remediation.
References If there are any questions or comments about this advisory, contact AWS Security via the vulnerability reporting page or directly via email to aws-security@amazon.com. Please do not create a public GitHub issue.
Other sources
Unbounded memory allocation in the CRYPTO frame reassembler in s2n-quic before 1.8.2 may allow an unauthenticated remote actor to cause a denial of service (degraded availability) by sending crafted QUIC Initial packets.
To remediate this issue, users should upgrade to v1.8.2.
— MITRE
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
rust/s2n-quicto a version that resolves this vulnerability.Fixed in 1.82.0 - Upgrade
Upgrade
s2n-quicto a version that resolves this vulnerability.Fixed in v1.82.0 - Upgrade
Upgrade
s2n-quicto a version that resolves this vulnerability.Fixed in v1.8.2
Event History
Frequently Asked Questions
What is the severity of CVE-2026-10740?
The severity of CVE-2026-10740 is medium with a score of 5.3.
How do I fix CVE-2026-10740?
To fix CVE-2026-10740, users should upgrade to version 1.8.2 of Amazon s2n-quic.
What type of vulnerability is CVE-2026-10740?
CVE-2026-10740 is characterized by excessive memory allocation that can lead to a denial of service.
What impact does CVE-2026-10740 have on availability?
CVE-2026-10740 can cause degraded availability due to unbounded memory allocation.
Who is affected by CVE-2026-10740?
Users of Amazon s2n-quic prior to version 1.8.2 are affected by CVE-2026-10740.