What is CVE-2026-16318?

CVE-2026-16318 is a medium-severity vulnerability in Amazon S2n-tls, classified under Missing Release of Memory after Effective Lifetime. CVSS score: 5.3/10. Published 2026-07-21.

How severe is CVE-2026-16318?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Vulnerability in Amazon S2n-tls

CVE-2026-16318

The QUIC transport parameters extension handler in s2n-tls incorrectly uses s2n_alloc instead of s2n_realloc to store the peer's transport parameters. When a TLS 1.3 connection goes through a HelloRetryRequest, the handler is called twice…

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.

Affected products

Amazon S2n-tls — versions 0

Weakness classification (CWE)

CWE-401 — Missing Release of Memory after Effective Lifetime

References

ff89ba41-3aa1-4d27-914a-91399e9639e5 (release-notes, patch)
ff89ba41-3aa1-4d27-914a-91399e9639e5 (vendor-advisory)
ff89ba41-3aa1-4d27-914a-91399e9639e5 (release-notes)

Frequently asked questions

What is CVE-2026-16318?: CVE-2026-16318 is a medium-severity vulnerability in Amazon S2n-tls, classified under Missing Release of Memory after Effective Lifetime. CVSS score: 5.3/10. Published 2026-07-21.
How severe is CVE-2026-16318?: Medium severity. CVSS v3 base score is 5.3 out of 10.