Buffer Overflow Affecting ngtcp2/ngtcp2 package, versions [,1.22.1)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-UNMANAGED-NGTCP2NGTCP2-16323270
- published30 Apr 2026
- disclosed16 Apr 2026
- creditKherrisan
Introduced: 16 Apr 2026
CVE-2026-40170 (opens in a new tab)How to fix?
Upgrade ngtcp2/ngtcp2 to version 1.22.1 or higher.
Overview
Affected versions of this package are vulnerable to Buffer Overflow in the qlog process when handling untrusted QUIC peer transport parameters. An attacker can cause a denial of service by sending specially crafted, large transport parameters that trigger writes beyond a fixed-size buffer. This is only exploitable if the qlog callback is enabled during compilation and runtime.
Workaround
This vulnerability can be mitigated by disabling the qlog callback in applications utilizing the affected library and restarting the applications.