CVE-2026-12413: libreswan Off-by-one Error
Vulnerability summary
CVE-2026-12413 is a high (CVSS 7.5) Off-by-one Error vulnerability in libreswan. EPSS estimates a 0.60% chance of exploitation in the next 30 days, higher than 47.5% of scored vulnerabilities.
Advisory lineage
Upstream 0 · Downstream 9Timeline
- 02-07-2026PublishedVulnerability first disclosed.
- 07-07-2026Last modifiedVulnerability information updated.
Description
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]. 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.
CVSS metrics
4 scores · 4 sources · 1 version- OSV · UbuntuEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- OSV · DebianEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- NVDNIST7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
0.60%
Chance of exploitation in the next 30 days
Percentile
48%
Versus all other CVEs
30-day change
0.00 pp
From 0.60% on 19-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-193Off-by-one ErrorA product calculates or uses an incorrect maximum or minimum value that is 1 more, or 1 less, than the correct value.
- CWE-617Reachable AssertionThe product contains an assert() or similar statement that can be triggered by an attacker, which leads to an application exit or other behavior that is more severe than necessary.
Affected systems
Debian1 product
- libreswanAll versions (No fix recorded) | < 5.2-2.5
Libreswan1 product
- libreswan≥ 4.6, < 5.3.1
The libreswan project1 product
- libreswan≥ 4.6, ≤ 5.3
Ubuntu1 product
- libreswanAll versions (No fix recorded)
4 vendors · 4 products
