CVE-2026-40170
Publication date 16 April 2026
Last updated 27 May 2026
Ubuntu priority
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.
Status
| Package | Ubuntu Release | Status |
|---|---|---|
| ngtcp2 | 26.04 LTS resolute |
Fixed 1.16.0-1ubuntu0.1
|
| 25.10 questing |
Fixed 1.11.0-1+deb13u1build0.25.10.1
|
|
| 24.04 LTS noble |
Fixed 0.12.1+dfsg-1+deb12u1build0.24.04.1
|
|
| 22.04 LTS jammy |
Fixed 0.1.0+dfsg-1ubuntu0.1~esm1
|
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| Parameter | Value |
|---|---|
| Base score |
7.5 · High
|
| Attack vector | Network |
| Attack complexity | Low |
| Privileges required | None |
| User interaction | None |
| Scope | Unchanged |
| Confidentiality | None |
| Integrity impact | None |
| Availability impact | High |
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
References
Related Ubuntu Security Notices (USN)
- USN-8300-1
- ngtcp2 vulnerability
- 25 May 2026