CVE-2026-40170 (GCVE-0-2026-40170)
Vulnerability from cvelistv5 – Published: 2026-04-16 21:34 – Updated: 2026-07-15 01:01
VLAI
EPSS
VEX
Title
ngtcp2 has a qlog transport parameter serialization stack buffer overflow
Summary
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.
Severity
7.5 (High)
SSVC
Exploitation: poc
Automatable: yes
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-04-17 14:52 UTC
CWE
Assigner
References
9 references
| URL | Tags |
|---|---|
| https://github.com/ngtcp2/ngtcp2/security/advisor… | x_refsource_CONFIRM |
| https://github.com/ngtcp2/ngtcp2/commit/708a7640c… | x_refsource_MISC |
| http://www.openwall.com/lists/oss-security/2026/0… | |
| https://access.redhat.com/security/cve/CVE-2026-40170 | vdb-entryx_refsource_REDHAT |
| https://bugzilla.redhat.com/show_bug.cgi?id=2459061 | issue-trackingx_refsource_REDHAT |
| https://security.access.redhat.com/data/csaf/v2/v… | x_sadp-csaf-vex |
| https://access.redhat.com/errata/RHSA-2026:22963 | vendor-advisoryx_refsource_REDHAT |
| https://access.redhat.com/errata/RHSA-2026:25049 | vendor-advisoryx_refsource_REDHAT |
| https://access.redhat.com/errata/RHSA-2026:9113 | vendor-advisoryx_refsource_REDHAT |
Impacted products
7 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| ngtcp2 | ngtcp2 |
Affected:
< 1.22.1
|
guessed | |
| Red Hat | Red Hat Enterprise Linux 10 |
Unaffected:
0:4.23.5-109.el10_2 , < *
(rpm)
cpe:/o:redhat:enterprise_linux:10.2 |
||
| Red Hat | Red Hat Enterprise Linux 9 |
Unaffected:
0:4.23.5-10.el9_8 , < *
(rpm)
cpe:/a:redhat:enterprise_linux:9 cpe:/o:redhat:enterprise_linux:9 |
||
| Red Hat | Red Hat Hardened Images |
Unaffected:
1.22.1-1.hum1 , < *
(rpm)
cpe:/a:redhat:hummingbird:1 |
||
| Red Hat | Red Hat Enterprise Linux 10 |
cpe:/o:redhat:enterprise_linux:10
|
||
| Red Hat | Red Hat Enterprise Linux 8 |
cpe:/o:redhat:enterprise_linux:8
|
||
| Red Hat | Red Hat Enterprise Linux 9 |
cpe:/o:redhat:enterprise_linux:9
|
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}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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