VDB
CVE-2026-40170
CVE-2026-40170
PUBLISHED
CVSS 7.5 HIGH
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.
EPSS 0.02% · 7.0th percentile
Risk Scores
CVSS v3.1
7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS Score
0.02%
7.0th percentile
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| ngtcp2 | ngtcp2 | < 1.22.1 |
Timeline
- Apr 16, 2026 CVE Published
- Apr 17, 2026 PoC Published
- Apr 19, 2026 Security Advisory
- Apr 20, 2026 CVE Updated
- May 18, 2026 EPSS Score
- May 19, 2026 EPSS Score
- May 20, 2026 EPSS Score
- May 21, 2026 EPSS Score
- May 22, 2026 EPSS Score
- May 23, 2026 EPSS Score
- May 24, 2026 EPSS Score
- May 25, 2026 EPSS Score