01 Record

CVE-2026-40170

ngtcp2 has a qlog transport parameter serialization stack buffer overflow

HighPUBLISHEDCNA: GitHub_M

CNA base score7.5 CVSS v3.xCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

View raw JSON

02 Description

ngtcp2 has a qlog transport parameter serialization stack buffer overflow

03 Exploitation and scoring

Exploitation

Public exploit code exists. CISA's assessment records a public proof of concept. That is not a report of exploitation in the wild.

SSVC decision

ExploitationpocPublic proof-of-concept exploit code exists. Not a report of exploitation in the wild.
AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.

CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.

EPSS probability

0.77% probability of exploitation activity in the next 30 days.

EPSS percentile

Equal to or higher than the score of 55.5% of scored records. A rank, not a probability.

NVD base score

7.5 (CVSS v3.x), scored by the NVD independently of the CNA.

NVD CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

NVD analysis status

Modified. NVD last modified this record on 2026-07-15.

Red Hat severity

Important. Red Hat's rating for its own products, not a CVSS rating.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published

2026-04-16 21:34Z6 MO AGO

Last updated

2026-07-15 01:01Z3 MO AGO

Reserved

2026-04-09

Assigning CNA

GitHub_M

Record state

PUBLISHED

Severity

High (CVSS 7.5)

CNA CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Weaknesses

CWE-121Stack-based Buffer OverflowVariant
CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')Base

Data version

5.2

Document digest

85c07149b48d7d81a9b39397d4eee8b76179cde13fbc4ffb2687508754872b01

05 Affected products

VendorProductVersionsPlatforms

ngtcp2ngtcp2< 1.22.1—

06 References

github.comhttps://github.com/ngtcp2/ngtcp2/security/advisories/GHSA-f523-465f-8c8fx_refsource_CONFIRM
github.comhttps://github.com/ngtcp2/ngtcp2/commit/708a7640c1f48fb8ffb540c4b8ea5b4c1dfb8ee5x_refsource_MISC
www.openwall.comhttp://www.openwall.com/lists/oss-security/2026/04/17/12
access.redhat.comhttps://access.redhat.com/security/cve/CVE-2026-40170vdb-entryx_refsource_REDHAT
bugzilla.redhat.comRHBZ#2459061https://bugzilla.redhat.com/show_bug.cgi?id=2459061issue-trackingx_refsource_REDHAT
security.access.redhat.comhttps://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-40170.jsonx_sadp-csaf-vex
access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:22963vendor-advisoryx_refsource_REDHAT
access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:25049vendor-advisoryx_refsource_REDHAT
access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:9113vendor-advisoryx_refsource_REDHAT

07 Fixed in

AlmaLinux 9

ldb-tools
Fixed in 4.23.5-10.el9_8
libldb
Fixed in 4.23.5-10.el9_8
libldb-devel
Fixed in 4.23.5-10.el9_8
libnetapi
Fixed in 4.23.5-10.el9_8
libnetapi-devel
Fixed in 4.23.5-10.el9_8
libsmbclient
Fixed in 4.23.5-10.el9_8
libsmbclient-devel
Fixed in 4.23.5-10.el9_8
libwbclient
Fixed in 4.23.5-10.el9_8
libwbclient-devel
Fixed in 4.23.5-10.el9_8
python3-ldb
Fixed in 4.23.5-10.el9_8
python3-samba
Fixed in 4.23.5-10.el9_8
python3-samba-dc
Fixed in 4.23.5-10.el9_8
python3-samba-test
Fixed in 4.23.5-10.el9_8
samba
Fixed in 4.23.5-10.el9_8
samba-client
Fixed in 4.23.5-10.el9_8
samba-client-libs
Fixed in 4.23.5-10.el9_8
samba-common
Fixed in 4.23.5-10.el9_8
samba-common-libs
Fixed in 4.23.5-10.el9_8
samba-common-tools
Fixed in 4.23.5-10.el9_8
samba-dc-libs
Fixed in 4.23.5-10.el9_8
samba-dcerpc
Fixed in 4.23.5-10.el9_8
samba-devel
Fixed in 4.23.5-10.el9_8
samba-gpupdate
Fixed in 4.23.5-10.el9_8
samba-krb5-printing
Fixed in 4.23.5-10.el9_8
samba-ldb-ldap-modules
Fixed in 4.23.5-10.el9_8
samba-libs
Fixed in 4.23.5-10.el9_8
samba-pidl
Fixed in 4.23.5-10.el9_8
samba-test
Fixed in 4.23.5-10.el9_8
samba-test-libs
Fixed in 4.23.5-10.el9_8
samba-tools
Fixed in 4.23.5-10.el9_8
samba-usershares
Fixed in 4.23.5-10.el9_8
samba-vfs-iouring
Fixed in 4.23.5-10.el9_8
samba-winbind
Fixed in 4.23.5-10.el9_8
samba-winbind-clients
Fixed in 4.23.5-10.el9_8
samba-winbind-krb5-locator
Fixed in 4.23.5-10.el9_8
samba-winbind-modules
Fixed in 4.23.5-10.el9_8
samba-winexe
Fixed in 4.23.5-10.el9_8

AlmaLinux 10

ldb-tools
Fixed in 4.23.5-109.el10_2
libldb
Fixed in 4.23.5-109.el10_2
libldb-devel
Fixed in 4.23.5-109.el10_2
libnetapi
Fixed in 4.23.5-109.el10_2
libnetapi-devel
Fixed in 4.23.5-109.el10_2
libsmbclient
Fixed in 4.23.5-109.el10_2
libsmbclient-devel
Fixed in 4.23.5-109.el10_2
libwbclient
Fixed in 4.23.5-109.el10_2
libwbclient-devel
Fixed in 4.23.5-109.el10_2
python3-ldb
Fixed in 4.23.5-109.el10_2
python3-samba
Fixed in 4.23.5-109.el10_2
python3-samba-dc
Fixed in 4.23.5-109.el10_2
python3-samba-test
Fixed in 4.23.5-109.el10_2
samba
Fixed in 4.23.5-109.el10_2
samba-client
Fixed in 4.23.5-109.el10_2
samba-client-libs
Fixed in 4.23.5-109.el10_2
samba-common
Fixed in 4.23.5-109.el10_2
samba-common-libs
Fixed in 4.23.5-109.el10_2
samba-common-tools
Fixed in 4.23.5-109.el10_2
samba-dc-libs
Fixed in 4.23.5-109.el10_2
samba-dcerpc
Fixed in 4.23.5-109.el10_2
samba-devel
Fixed in 4.23.5-109.el10_2
samba-gpupdate
Fixed in 4.23.5-109.el10_2
samba-krb5-printing
Fixed in 4.23.5-109.el10_2
samba-ldb-ldap-modules
Fixed in 4.23.5-109.el10_2
samba-libs
Fixed in 4.23.5-109.el10_2
samba-pidl
Fixed in 4.23.5-109.el10_2
samba-test
Fixed in 4.23.5-109.el10_2
samba-test-libs
Fixed in 4.23.5-109.el10_2
samba-tools
Fixed in 4.23.5-109.el10_2
samba-usershares
Fixed in 4.23.5-109.el10_2
samba-vfs-iouring
Fixed in 4.23.5-109.el10_2
samba-winbind
Fixed in 4.23.5-109.el10_2
samba-winbind-clients
Fixed in 4.23.5-109.el10_2
samba-winbind-krb5-locator
Fixed in 4.23.5-109.el10_2
samba-winbind-modules
Fixed in 4.23.5-109.el10_2
samba-winexe
Fixed in 4.23.5-109.el10_2

CloudLinux 9

ldb-tools
Fixed in 4.23.5-10.el9_8
libldb
Fixed in 4.23.5-10.el9_8
libldb-devel
Fixed in 4.23.5-10.el9_8
libnetapi
Fixed in 4.23.5-10.el9_8
libnetapi-devel
Fixed in 4.23.5-10.el9_8
libsmbclient
Fixed in 4.23.5-10.el9_8
libsmbclient-devel
Fixed in 4.23.5-10.el9_8
libwbclient
Fixed in 4.23.5-10.el9_8
libwbclient-devel
Fixed in 4.23.5-10.el9_8
python3-ldb
Fixed in 4.23.5-10.el9_8
python3-samba
Fixed in 4.23.5-10.el9_8
python3-samba-dc
Fixed in 4.23.5-10.el9_8
python3-samba-test
Fixed in 4.23.5-10.el9_8
samba
Fixed in 4.23.5-10.el9_8
samba-client
Fixed in 4.23.5-10.el9_8
samba-client-libs
Fixed in 4.23.5-10.el9_8
samba-common
Fixed in 4.23.5-10.el9_8
samba-common-libs
Fixed in 4.23.5-10.el9_8
samba-common-tools
Fixed in 4.23.5-10.el9_8
samba-dc-libs
Fixed in 4.23.5-10.el9_8
samba-dcerpc
Fixed in 4.23.5-10.el9_8
samba-devel
Fixed in 4.23.5-10.el9_8
samba-gpupdate
Fixed in 4.23.5-10.el9_8
samba-krb5-printing
Fixed in 4.23.5-10.el9_8
samba-ldb-ldap-modules
Fixed in 4.23.5-10.el9_8
samba-libs
Fixed in 4.23.5-10.el9_8
samba-pidl
Fixed in 4.23.5-10.el9_8
samba-test
Fixed in 4.23.5-10.el9_8
samba-test-libs
Fixed in 4.23.5-10.el9_8
samba-tools
Fixed in 4.23.5-10.el9_8
samba-usershares
Fixed in 4.23.5-10.el9_8
samba-vfs-iouring
Fixed in 4.23.5-10.el9_8
samba-winbind
Fixed in 4.23.5-10.el9_8
samba-winbind-clients
Fixed in 4.23.5-10.el9_8
samba-winbind-krb5-locator
Fixed in 4.23.5-10.el9_8
samba-winbind-modules
Fixed in 4.23.5-10.el9_8
samba-winexe
Fixed in 4.23.5-10.el9_8

Derived from AlmaLinux 9. Partial coverage: only packages taken from AlmaLinux 9 are listed.

CloudLinux 10

ldb-tools
Fixed in 4.23.5-109.el10_2
libldb
Fixed in 4.23.5-109.el10_2
libldb-devel
Fixed in 4.23.5-109.el10_2
libnetapi
Fixed in 4.23.5-109.el10_2
libnetapi-devel
Fixed in 4.23.5-109.el10_2
libsmbclient
Fixed in 4.23.5-109.el10_2
libsmbclient-devel
Fixed in 4.23.5-109.el10_2
libwbclient
Fixed in 4.23.5-109.el10_2
libwbclient-devel
Fixed in 4.23.5-109.el10_2
python3-ldb
Fixed in 4.23.5-109.el10_2
python3-samba
Fixed in 4.23.5-109.el10_2
python3-samba-dc
Fixed in 4.23.5-109.el10_2
python3-samba-test
Fixed in 4.23.5-109.el10_2
samba
Fixed in 4.23.5-109.el10_2
samba-client
Fixed in 4.23.5-109.el10_2
samba-client-libs
Fixed in 4.23.5-109.el10_2
samba-common
Fixed in 4.23.5-109.el10_2
samba-common-libs
Fixed in 4.23.5-109.el10_2
samba-common-tools
Fixed in 4.23.5-109.el10_2
samba-dc-libs
Fixed in 4.23.5-109.el10_2
samba-dcerpc
Fixed in 4.23.5-109.el10_2
samba-devel
Fixed in 4.23.5-109.el10_2
samba-gpupdate
Fixed in 4.23.5-109.el10_2
samba-krb5-printing
Fixed in 4.23.5-109.el10_2
samba-ldb-ldap-modules
Fixed in 4.23.5-109.el10_2
samba-libs
Fixed in 4.23.5-109.el10_2
samba-pidl
Fixed in 4.23.5-109.el10_2
samba-test
Fixed in 4.23.5-109.el10_2
samba-test-libs
Fixed in 4.23.5-109.el10_2
samba-tools
Fixed in 4.23.5-109.el10_2
samba-usershares
Fixed in 4.23.5-109.el10_2
samba-vfs-iouring
Fixed in 4.23.5-109.el10_2
samba-winbind
Fixed in 4.23.5-109.el10_2
samba-winbind-clients
Fixed in 4.23.5-109.el10_2
samba-winbind-krb5-locator
Fixed in 4.23.5-109.el10_2
samba-winbind-modules
Fixed in 4.23.5-109.el10_2
samba-winexe
Fixed in 4.23.5-109.el10_2

Derived from AlmaLinux 10. Partial coverage: only packages taken from AlmaLinux 10 are listed.

Debian 12

ngtcp2
Fixed in 0.12.1+dfsg-1+deb12u1

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 13

ngtcp2
Fixed in 1.11.0-1+deb13u1

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 14

ngtcp2
Fixed in 1.22.1-1

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 24.04 LTS

ngtcp2
Fixed in 0.12.1+dfsg-1+deb12u1build0.24.04.1

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 25.10

ngtcp2
Fixed in 1.11.0-1+deb13u1build0.25.10.1

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 26.04 LTS

ngtcp2
Fixed in 1.16.0-1ubuntu0.1

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu Pro 22.04 LTS

ngtcp2
Fixed in 0.1.0+dfsg-1ubuntu0.1~esm1
Available with Ubuntu Pro: https://ubuntu.com/pro

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

A release or ecosystem missing from this list has no record here. It may be unaffected or not covered by the source. Source notices and licences.