# CVE-2026-16317: Silent Drop of TLS 1.3 Encrypted Records in s2n-tls

> CVE-2026-16317: Silent Drop of TLS 1.3 Encrypted Records in s2n-tls. CVSS 6.5 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-16317
Last updated: 2026-10-24T19:10:00Z

- Published: 2026-07-21 20:12 UTC · Updated: 2026-10-24 19:10 UTC · Assigner: AMZN
- CVSS: 6.5 (CVSS 3.1) · Severity: Medium · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:L
- EPSS: 0.25%, 16th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-354

## Description

Missing validation of the outer content\_type byte on TLS 1.3 encrypted records in s2n-tls allows an active man-in-the-middle to silently discard individual application data records without either endpoint detecting the modification. RFC 8446 Section 5.2 requires that the outer content\_type of all encrypted TLS 1.3 records must be application\_data (0x17). The s2n-tls AEAD implementation hardcodes this value in the additional authenticated data rather than using the actual wire byte, so the outer content\_type is not covered by the authentication tag.  This enables selective suppression of application data. In HTTP pipelining scenarios, dropping a TLS record containing an HTTP request can cause request/response desynchronization, where subsequent responses are delivered to the wrong requests. In write-heavy workloads, a dropped record containing a write request can result in undetectable data loss when the client interprets a subsequent success response as confirmation of the dropped write. All TLS 1.3 connections are affected. Both TLS clients and servers are affected. TLS 1.2 and QUIC connections are not affected. We recommend you upgrade s2n-tls to version v1.7.6

## Affected vendors and products

- AWS: s2n-tls

## Tracked companies

- [Amazon Web Services](https://rewindex.com/company/aws.md)

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-16317)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-16317)
- [https://aws.amazon.com/security/security-bulletins/2026-062-aws/](https://aws.amazon.com/security/security-bulletins/2026-062-aws/)
- [https://github.com/aws/s2n-tls/releases/tag/v1.7.6](https://github.com/aws/s2n-tls/releases/tag/v1.7.6)
- [https://github.com/aws/s2n-tls/security/advisories/GHSA-684c-v35q-fvx7](https://github.com/aws/s2n-tls/security/advisories/GHSA-684c-v35q-fvx7)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2026-16317 · Markdown: https://rewindex.com/cve/CVE-2026-16317.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-16317 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T04:05:41.254Z