CVE-2026-55991 Remote DNS-over-QUIC (DoQ) flow-control assertion failure in libngtcp2

In NLnet Labs Unbound 1.22.0 up to and including 1.25.1, a remote unauthenticated client can trigger a libngtcp2 assertion if compiled with assertions on and terminate the entire Unbound process using a single DNS-over-QUIC DoQ connection and one normal DNS query. This is caused by an erroneous...

CVE-2026-16318

The QUIC transport parameters extension handler in s2n-tls incorrectly uses s2nalloc instead of s2nrealloc to store the peer's transport parameters. When a TLS 1.3 connection goes through a HelloRetryRequest, the handler is called twice on the same connection. On the second call, s2nalloc zeroes...

CVE-2026-16318 QUIC Transport Parameters Memory Leak During HelloRetryRequest in s2n-tls

The QUIC transport parameters extension handler in s2n-tls incorrectly uses s2nalloc instead of s2nrealloc to store the peer's transport parameters. When a TLS 1.3 connection goes through a HelloRetryRequest, the handler is called twice on the same connection. On the second call, s2nalloc zeroes...

CVE-2026-16318

The CVE-2026-16318 issue affects server-side QUIC deployments using s2n-tls, where the QUIC transport parameters extension handler uses s2n_alloc instead of s2n_realloc. During TLS 1.3 HelloRetryRequest, the handler runs twice on the same connection; on the second run it zeroes the existing point...

PT-2026-62072

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 on the same connection. On the second call, s2n alloc zero...

ngtcp2: ngtcp2: Denial of service via stack buffer overflow during QUIC handshake

A flaw was found in ngtcp2, a C implementation of the IETF QUIC Quick UDP Internet Connections protocol. A remote attacker can exploit a stack buffer overflow vulnerability by sending specially crafted, large transport parameters during the QUIC handshake. This occurs when the qlog callback is...

ngtcp2: ngtcp2: Denial of service via stack buffer overflow during QUIC handshake

A flaw was found in ngtcp2, a C implementation of the IETF QUIC Quick UDP Internet Connections protocol. A remote attacker can exploit a stack buffer overflow vulnerability by sending specially crafted, large transport parameters during the QUIC handshake. This occurs when the qlog callback is...

USN-8300-1 ngtcp2 vulnerability

Zou Dikai discovered that ngtcp2 serialized peer transport parameters into a fixed 1024-byte stack buffer without bounds checking. When qlog was enabled, a remote attacker could possibly use this issue to execute arbitrary code...

Important: ngtcp2

Issue Overview: ngtcp2 is a C implementation of the IETF QUIC protocol. In versions prior to 1.22.1, ngtcp2qlogparameterssettransportparams serializes peer transport parameters into a fixed 1024-byte stack buffer without bounds checking. When qlog is enabled, a remote peer can send sufficiently...

ngtcp2: ngtcp2: Denial of service via stack buffer overflow during QUIC handshake

A flaw was found in ngtcp2, a C implementation of the IETF QUIC Quick UDP Internet Connections protocol. A remote attacker can exploit a stack buffer overflow vulnerability by sending specially crafted, large transport parameters during the QUIC handshake. This occurs when the qlog callback is...

SUSE CVE-2026-40170

ngtcp2 is a C implementation of the IETF QUIC protocol. In versions prior to 1.22.1, ngtcp2qlogparameterssettransportparams 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...

CVE-2026-40170

A flaw was found in ngtcp2, a C implementation of the IETF QUIC Quick UDP Internet Connections protocol. A remote attacker can exploit a stack buffer overflow vulnerability by sending specially crafted, large transport parameters during the QUIC handshake. This occurs when the qlog callback is...

DEBIAN-CVE-2026-40170

ngtcp2 is a C implementation of the IETF QUIC protocol. In versions prior to 1.22.1, ngtcp2qlogparameterssettransportparams 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...

ALPINE-CVE-2026-40170

ngtcp2 is a C implementation of the IETF QUIC protocol. In versions prior to 1.22.1, ngtcp2qlogparameterssettransportparams 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...

CVE-2026-40170

ngtcp2 is a C implementation of the IETF QUIC protocol. In versions prior to 1.22.1, ngtcp2qlogparameterssettransportparams 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...

CVE-2026-40170 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, ngtcp2qlogparameterssettransportparams 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...

CVE-2026-40170 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, ngtcp2qlogparameterssettransportparams 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...

CVE-2026-40170

ngtcp2 is a C implementation of the IETF QUIC protocol. In versions prior to 1.22.1, ngtcp2qlogparameterssettransportparams 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...

CVE-2026-40170

ngtcp2 (QUIC) vulnerability: in versions before 1.22.1, ngtcp2_qlog_parameters_set_transport_params() writes peer transport parameters into a fixed 1024-byte stack buffer without bounds checking, enabling a stack buffer overflow when qlog is enabled and large untrusted parameters are received dur...

CVE-2026-40170

ngtcp2 is a C implementation of the IETF QUIC protocol. In versions prior to 1.22.1, ngtcp2qlogparameterssettransportparams 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...