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NVD / CVE Program· CNA libreswan

CVE-2026-12413: IKEv2 Denial of Service via malformed fragmentation

Noroxi assessment

Priority: Monitor (action score 30/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.59% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: azl3 libreswan 4.15-1 on Azure Linux 3.0 4.15-2.

Low priority for now. Upgrade to azl3 libreswan 4.15-1 on Azure Linux 3.0 4.15-2 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

HighCVSS 7.5 · v3.1—No exploit Fix available
Published
Jul 2, 2026
Updated
Oct 25, 2026
EPSS
0.5% · 48th percentile

Report tools

JSON

Action score

30

Monitor

Low priority for now.

CVSS
30 / 40 · 7.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.5%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · libreswan
7.5
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-12413

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
libreswanlibreswan

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • libreswan libreswan4.6 and later · before 5.3.1

Versions reported by the vendor

Affected version ranges reported by the assigning authority (libreswan). Independent of NVD's CPE analysis and usually ahead of it.

  • The Libreswan Project libreswan

    • 5.3.1not affected
    • 4.6 and later · up to and including 5.3affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
AlmaLinux:10libreswanbefore 5.3.2-1.el10_25.3.2-1.el10_2
AlmaLinux:10libreswan-minimalbefore 5.3.2-1.el10_25.3.2-1.el10_2
AlmaLinux:8libreswanbefore 4.12-2.el8_10.64.12-2.el8_10.6
AlmaLinux:9libreswanbefore 4.15-10.el9_84.15-10.el9_8
Debian:12libreswanfrom 0—
Debian:14libreswanbefore 5.2-2.55.2-2.5
Red Hat:enterprise_linux_eus:10.0libreswanbefore 0:5.2-1.el10_0.50:5.2-1.el10_0.5
Red Hat:enterprise_linux:10.2libreswanbefore 0:5.3.2-1.el10_20:5.3.2-1.el10_2
Red Hat:enterprise_linux:10.2libreswan-debugsourcebefore 0:5.3.2-1.el10_20:5.3.2-1.el10_2
Red Hat:enterprise_linux:10.2libreswan-minimalbefore 0:5.3.2-1.el10_20:5.3.2-1.el10_2
Red Hat:enterprise_linux:10.2libreswan-minimal-debuginfobefore 0:5.3.2-1.el10_20:5.3.2-1.el10_2
Red Hat:enterprise_linux:8::appstreamlibreswanbefore 0:4.12-2.el8_10.60:4.12-2.el8_10.6
Red Hat:enterprise_linux:8::appstreamlibreswan-debuginfobefore 0:4.12-2.el8_10.60:4.12-2.el8_10.6
Red Hat:enterprise_linux:8::appstreamlibreswan-debugsourcebefore 0:4.12-2.el8_10.60:4.12-2.el8_10.6
Red Hat:enterprise_linux:9::appstreamlibreswanbefore 0:4.15-10.el9_80:4.15-10.el9_8
Red Hat:enterprise_linux:9::appstreamlibreswan-debuginfobefore 0:4.15-10.el9_80:4.15-10.el9_8
Red Hat:enterprise_linux:9::appstreamlibreswan-debugsourcebefore 0:4.15-10.el9_80:4.15-10.el9_8
Red Hat:enterprise_linux:9::fastdatapathlibreswanbefore 0:5.3.2-1.el9fdp0:5.3.2-1.el9fdp
Red Hat:enterprise_linux:9::fastdatapathlibreswan-debuginfobefore 0:5.3.2-1.el9fdp0:5.3.2-1.el9fdp
Red Hat:enterprise_linux:9::fastdatapathlibreswan-debugsourcebefore 0:5.3.2-1.el9fdp0:5.3.2-1.el9fdp
Red Hat:rhel_e4s:8.8::appstreamlibreswanbefore 0:4.9-3.el8_8.30:4.9-3.el8_8.3
Red Hat:rhel_e4s:9.2::appstreamlibreswanbefore 0:4.9-5.el9_2.50:4.9-5.el9_2.5
Red Hat:rhel_e4s:9.4::appstreamlibreswanbefore 0:4.12-3.el9_4.20:4.12-3.el9_4.2
Red Hat:rhel_eus:9.6::appstreamlibreswanbefore 0:4.15-8.el9_6.10:4.15-8.el9_6.1

+3

Same product

libreswan: all records

Other highest-scoring records for the same primary product.

  • CVE-2013-7283Race condition in the libreswan.spec files for Red Hat Enterprise Linux (RHEL) and Fedora packages in libreswan 3.6 has unspecified impact a
    37Monitor
  • CVE-2022-23094Libreswan 4.2 through 4.5 allows remote attackers to cause a denial of service (NULL pointer dereference and daemon crash) via a crafted IKE
    31Monitor
  • CVE-2020-1763An out-of-bounds buffer read flaw was found in the pluto daemon of libreswan from versions 3.27 till 3.31 where, an unauthenticated attacker
    31Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2023-38712Aug 25, 2023 · An issue was discovered in Libreswan 3.x and 4.x before 4.12.
    26Monitor
  • ← EarlierCVE-2024-3652Apr 10, 2024 · IKEv1 default AH/ESP responder can cause libreswan to abort and restart
    26Monitor
  • Later →CVE-2026-50721Jul 2, 2026 · IKEv1 Denial of Service via RSA-SHA1 (PKCS#1 Version 1.5 Encrypted) authentication payload
    23Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
azl3 libreswan 4.15-1 on Azure Linux 3.04.15-2 · CBL-Mariner ReleasesMicrosoft (MSRC)
almalinux:libreswan4.12-2.el8_10.6 · AlmaLinux:8Package registry (OSV)
almalinux:libreswan-minimal5.3.2-1.el10_2 · AlmaLinux:10Package registry (OSV)
debian:libreswan5.2-2.5 · Debian:14Package registry (OSV)
red hat:libreswan0:4.12-2.el8_10.6 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:libreswan-debuginfo0:4.12-2.el8_10.6 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:libreswan-debugsource0:4.12-2.el8_10.6 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:libreswan-minimal0:5.3.2-1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:libreswan-minimal-debuginfo0:5.3.2-1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
rocky linux:libreswan0:4.12-2.el8_10.6 · Rocky Linux:8Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-193 · Off-by-one Error

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (1 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records