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Ngtcp2 CVE-2026-40170

| EUVDEUVD-2026-23302 HIGH
Stack-based Buffer Overflow (CWE-121)
2026-04-16 GitHub_M
Stack Overflow Buffer Overflow Ngtcp2
7.5
CVSS 3.1 · Vendor: GitHub_M
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Severity by source

Vendor (GitHub_M) PRIMARY
7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SUSE
HIGH
qualitative
Red Hat
7.5 HIGH
qualitative

Primary rating from Vendor (GitHub_M).

CVSS VectorVendor: GitHub_M

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

4
Patch released
Apr 20, 2026 - 16:16 nvd
Patch available
Patch available
Apr 16, 2026 - 22:46 EUVD
EUVD ID Assigned
Apr 16, 2026 - 22:00 euvd
EUVD-2026-23302
CVE Published
Apr 16, 2026 - 21:34 nvd
HIGH 7.5

DescriptionCVE.org

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.

Analysis

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.

Same weakness CWE-121 – Stack-based Buffer Overflow

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Same technique Stack Overflow

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CVE-2025-22457 CRITICAL POC
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CVE-2012-10053 CRITICAL POC
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CVE-2013-10064 CRITICAL POC
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CVE-2012-10023 MEDIUM POC
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CVE-2012-10058 CRITICAL POC
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Vendor StatusVendor

SUSE

Severity: High
Product Status
SUSE Linux Enterprise High Performance Computing 12 Fixed
SUSE Linux Enterprise High Performance Computing 15 SP7 Fixed
SUSE Linux Enterprise High Performance Computing 15 SP7 Fixed
SUSE Linux Enterprise Module for Web and Scripting 15 SP7 Fixed
SUSE Linux Enterprise Module for Web and Scripting 15 SP7 Fixed

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CVE-2026-40170 vulnerability details – vuln.today
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