CVE-2026-40170ngtcp2 is a C implementation of the IETF QUIC protocol.
Updated under an hour ago ()
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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
- 7.5 HIGH (v3.1, NVD)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Weakness (CWE)
- CWE-121, CWE-120
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Not given
- NVD analysis
- Modified
- Record last updated
- Jul 15, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
tatsuhiro-t ngtcp2 tatsuhiro-t:ngtcp2 | before 1.22.1 | NVD |
References
- https://github.com/ngtcp2/ngtcp2/commit/708a7640c1f48fb8ffb540c4b8ea5b4c1dfb8ee5patch
- https://github.com/ngtcp2/ngtcp2/security/advisories/GHSA-f523-465f-8c8fexploit, mitigation, patch, vendor-advisory
- http://www.openwall.com/lists/oss-security/2026/04/17/12exploit, mailing-list, mitigation, patch, third-party-advisory
- https://access.redhat.com/errata/RHSA-2026:22963
- https://access.redhat.com/errata/RHSA-2026:25049
- https://access.redhat.com/errata/RHSA-2026:9113
- https://access.redhat.com/security/cve/CVE-2026-40170
- https://bugzilla.redhat.com/show_bug.cgi?id=2459061
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-40170.json
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.