Bug 2459061 (CVE-2026-40170) - CVE-2026-40170 ngtcp2: ngtcp2: Denial of service via stack buffer overflow during QUIC handshake
Summary: CVE-2026-40170 ngtcp2: ngtcp2: Denial of service via stack buffer overflow du...
Keywords:
Status: NEW
Alias: CVE-2026-40170
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
high
high
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On: 2459282 2459283
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-04-16 22:01 UTC by OSIDB Bzimport
Modified: 2026-06-23 06:13 UTC (History)
2 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2026:22963 0 None None None 2026-06-03 20:58:06 UTC
Red Hat Product Errata RHSA-2026:25049 0 None None None 2026-06-10 11:14:54 UTC

Description OSIDB Bzimport 2026-04-16 22:01:19 UTC 
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.
Comment 9 errata-xmlrpc 2026-06-03 20:58:05 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:22963 https://access.redhat.com/errata/RHSA-2026:22963
Comment 10 errata-xmlrpc 2026-06-10 11:14:53 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:25049 https://access.redhat.com/errata/RHSA-2026:25049
Comment 11 TEJ RATHI 2026-06-23 06:13:30 UTC 
```

For Samba package, this vulnerability strictly affects environments running Red Hat Enterprise Linux (RHEL) 9.8 and newer, as well as RHEL 10.2 and newer. Only these versions ship with Samba 4.23 or above, which introduces native support for the integrated ngtcp2 library to handle SMB over QUIC functionality. Earlier versions of RHEL utilize older iterations of Samba that do not bundle or support ngtcp2 and are therefore unaffected.

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