CVE-2026-40170
HIGH EPSS 43.3%
Published Apr 16, 20262mo ago · Modified Jun 17, 20261w ago
7.5 CVSS 3.1
Published Apr 16, 2026 2mo ago
Last Modified Jun 17, 2026 1w ago
Description
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.
CVSS Details
Base Score
Exploitability
Impact
Vector string
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
Threat Intelligence
EPSS Exploit Probability
43.3% percentile
Exploit & Patch Status
Public Exploit Known
Patch Available
Weaknesses 1
CWE-121
Affected Products 1
| Vendor | Product | Version | Range |
|---|---|---|---|
| tatsuhiro-t | ngtcp2 | * | <1.22.1 |
References 3
- openwall.com http://www.openwall.com/lists/oss-security/2026/04/17/12
- github.com https://github.com/ngtcp2/ngtcp2/commit/708a7640c1f48fb8ffb540c4b8ea5b4c1dfb8ee5
- github.com https://github.com/ngtcp2/ngtcp2/security/advisories/GHSA-f523-465f-8c8f
Remediation
- openwall.com http://www.openwall.com/lists/oss-security/2026/04/17/12
- github.com https://github.com/ngtcp2/ngtcp2/commit/708a7640c1f48fb8ffb540c4b8ea5b4c1dfb8ee5
- github.com https://github.com/ngtcp2/ngtcp2/security/advisories/GHSA-f523-465f-8c8f