Off-by-one Error Affecting libreswan/libreswan package, versions [4.6,5.3.1)
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-LIBRESWANLIBRESWAN-17807926
- published3 Jul 2026
- disclosed2 Jul 2026
- creditUnknown
Introduced: 2 Jul 2026
CVE-2026-12413 (opens in a new tab)How to fix?
Upgrade libreswan/libreswan to version 5.3.1 or higher.
Overview
Affected versions of this package are vulnerable to Off-by-one Error via the reassemble_v2_incoming_fragments function. An attacker can cause the daemon to crash and restart repeatedly by sending specially crafted IKEv2 fragments, resulting in a persistent service outage. This is only exploitable if IKEv2 connections are configured without setting fragmentation=no.
Workaround
This vulnerability can be mitigated by adding fragmentation=no to all IKEv2 configurations if fragmentation is not needed.