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High ALAS2023-2026-1633 1 CVE

Important: ngtcp2 security update (Amazon Linux 2023)

Published Apr 27, 2026 · Updated Apr 30, 2026

Summary

Package updates are available for Amazon Linux 2023 that fix the following vulnerabilities: CVE-2026-40170: ngtcp2 is a C implementation of the IETF QUIC protocol. In versions prior to 1.22.1, ngtcp2_qlog_parameters_set_transport_params() serializes peer transport parameters into a fixed 1024-byte stack buffer without bounds checking. When qlog is enabled, a remote peer can send sufficiently large transport parameters during the QUIC handshake to cause writes beyond the buffer boundary, resulting in a stack buffer overflow. This affects deployments that enable the qlog callback and process untrusted peer transport parameters. This issue has been fixed in version 1.22.1. If developers are unable to immediately upgrade, they can disable the qlog on client.

Fixed packages 11

ReleasePackageFixed in
Amazon Linux · 2023 ngtcp2 0:1.21.0-1.amzn2023.0.2
Amazon Linux · 2023 ngtcp2-crypto-gnutls 0:1.21.0-1.amzn2023.0.2
Amazon Linux · 2023 ngtcp2-crypto-gnutls-debuginfo 0:1.21.0-1.amzn2023.0.2
Amazon Linux · 2023 ngtcp2-crypto-gnutls-devel 0:1.21.0-1.amzn2023.0.2
Amazon Linux · 2023 ngtcp2-crypto-ossl 0:1.21.0-1.amzn2023.0.2
Amazon Linux · 2023 ngtcp2-crypto-ossl-debuginfo 0:1.21.0-1.amzn2023.0.2
Amazon Linux · 2023 ngtcp2-crypto-ossl-devel 0:1.21.0-1.amzn2023.0.2
Amazon Linux · 2023 ngtcp2-debuginfo 0:1.21.0-1.amzn2023.0.2
Amazon Linux · 2023 ngtcp2-debugsource 0:1.21.0-1.amzn2023.0.2
Amazon Linux · 2023 ngtcp2-devel 0:1.21.0-1.amzn2023.0.2
Amazon Linux · 2023 ngtcp2-doc 0:1.21.0-1.amzn2023.0.2

Vulnerabilities 1

  • High 7.5

    ngtcp2 has a qlog transport parameter serialization stack buffer overflow

    ngtcp2 is a C implementation of the IETF QUIC protocol. In versions prior to 1.22.1, ngtcp2_qlog_parameters_set_transport_params() serializes peer transport parameters into a fixed 1024-byte stack buffer without bounds checking. When qlog is enabled, a remote…

References

  • web
    https://alas.aws.amazon.com/cve/html/CVE-2026-40170.html