Cyber Resilience

CVE-2026-12413

Libreswan 4.6 – 5.3.1

Published
02 July 2026
Modified
08 July 2026
Patch / advisory
View advisory
CVSS Score v3.1 7.5
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS Score 0.0060 46th percentile
Risk Priority 58 floored blend · peak EPSS

Summary

CVE-2026-12413 is a high-severity Off-by-one Error (CWE-193) vulnerability in Libreswan Libreswan. Its CVSS base score is 7.5 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked at the 46th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SA-15 (Development Process, Standards, and Tools) — see the control section below for these in your framework.

EU & UK References

Vulnerability Data

An invalidly formatted IKEv2 fragment causes the Libreswan pluto daemon to crash and restart. Continued exploitation would cause a denial of service. The function reassemble_v2_incoming_fragments() would ignore unknown outer payloads but still store these in a fixed size array msg_digest.digest[PAYLIMIT].…

more

An off-by-one error in the assertion PASSERT(logger, md->digest_roof < elemsof(md->digest)) causes the daemon to abort. No remote code execution is possible. Any configuration that allows IKEv2 connections that do not set fragmentation=no are vulnerable. IKEv1 is not affected.

CWE(s)
CWE-193CWE-617

Related Threats

MITRE ATT&CK Enterprise Techniques

T1499.004 Application or System Exploitation Impact
Adversaries may exploit software vulnerabilities that can cause an application or system to crash and deny availability to users.
attack.mitre.org →
T1499 Endpoint Denial of Service Impact
Adversaries may perform Endpoint Denial of Service (DoS) attacks to degrade or block the availability of services to users.
attack.mitre.org →
T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-50721Same product: Libreswan Libreswan
CVE-2026-50722Same product: Libreswan Libreswan
CVE-2024-3652Same product: Libreswan Libreswan
CVE-2023-38712Same product: Libreswan Libreswan
CVE-2023-38711Same product: Libreswan Libreswan
CVE-2023-30570Same product: Libreswan Libreswan
CVE-2023-38710Same product: Libreswan Libreswan
CVE-2023-23009Same product: Libreswan Libreswan
CVE-2026-52952Shared CWE-617
CVE-2026-10822Shared CWE-617

Affected Assets

libreswan
libreswan
4.6 — 5.3.1

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V6.2.1

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

Developer testing and evaluation can discover off-by-one errors in loops, bounds, and calculations before deployment.

SA-15 Development Process, Standards, and Tools partial match

Requiring documented development standards and tools can embed bounds-checking and arithmetic-correctness rules that stop off-by-one mistakes at introduction.

SA-8 Security and Privacy Engineering Principles partial match

Security engineering principles discourage use of assertions for handling untrusted input.

SI-10 Information Input Validation partial match

Validating untrusted inputs structurally prevents attacker data from reaching and triggering assertions.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly prevent off-by-one errors via reviews, static analysis, and testing.

DE.CM-09 partial match
prevents

Runtime monitoring of software can detect assertion-triggered crashes as adverse events.

ID.RA-01 partial match
prevents

Vulnerability identification processes can discover and record reachable-assertion flaws before deployment.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing in development and acceptance can detect off-by-one errors before release.

A.8.25 Secure development life cycle partial match
prevents

Secure development life cycle includes requirements and reviews that can catch off-by-one errors.

A.8.26 Application security requirements partial match
prevents

Application security requirements can specify bounds-checking and input validation to prevent off-by-one errors.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure system architecture and engineering principles promote defensive coding practices that reduce off-by-one mistakes.

A.8.28 Secure coding partial match
prevents

Secure coding directly addresses off-by-one errors through coding standards and peer review.

References