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TI-2026-73738 Aliases CVE-2026-94453GHSA-59fc-px6w-3g8v

Use-after-free in Libreswan IKE over TCP handling

Priority LOW 39CWE-416Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Partial Red Hat: 4 fixed, 5 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-416 and the CVSS impact.

Summary

Libreswan versions from 4.0 through 5.3.2 and version 5.4, when IKE over TCP is enabled with listen-tcp=yes, contain a use-after-free flaw (CWE-416). The pluto daemon keeps a pointer to an interface endpoint after a client closes its TCP connection, and using that pointer later crashes the daemon. A remote attacker can trigger it with a packet for the same connection before the peer authenticates, causing a denial of service and possibly remote code execution.

Written with Claude Haiku 5.5 from the sources below · 2026-11-07

Description from the CNA

Libreswan's pluto daemon has a use-after-free vulnerability when a client connecting using IKE over TCP closes the connection and another packet (retransmit or malicious) is received for the same tuple. IKE state is retained in memory after the client closes the connection, storing a pointer to iface_endpoint inside ike_sa.sa->st_iface_endpoint. Once this invalid pointer is used, the daemon crashes and restarts. This vulnerability can be triggered before the remote peer has authenticated itself. Continued exploitation can lead to a denial of service. Remote code execution could be possible. The IKE over TCP option is not enabled by default; only configurations that contain listen-tcp=yes are affected.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00454 39th percentileScored 2026-11-07
Fix Partial libreswan (The Libreswan Project): 5.3.3, 5.4.1Red Hat: 4 advisoriesRed Hat: 4 fixed, 5 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
The Libreswan Projectlibreswan4.0 – 5.3.2; 5.4 – 5.45.3.3, 5.4.1Patch availableCNA
  • libreswan VendorThe Libreswan Project Affected 4.0 – 5.3.2; 5.4 – 5.4 Fixed in 5.3.3, 5.4.1 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:a:libreswan:libreswan:*:*:*:*:*:*:*:*——The Libreswan Project

Remediation

Libreswan 5.3.3 and 5.4.1 fix this flaw. Red Hat fixes it in RHSA-2026:89748 for RHEL AppStream 9, RHSA-2026:89923 for RHEL AppStream 10, RHSA-2026:90492 for RHEL AppStream 8 and RHSA-2026:95346 for OpenShift Container Platform 4.22. Red Hat Enterprise Linux 6 has no fix planned, and Red Hat lists no fix available for Fast Datapath for RHEL 9, Red Hat Enterprise Linux 7, Red Hat OpenShift Container Platform 4 and Red Hat OpenShift Container Platform 5.

Written with Claude Haiku 5.5 from the sources below · 2026-11-07

  • Fix · CNA libreswan (The Libreswan Project) Fixed in 5.3.3, 5.4.1

Red Hat 4 advisories

  • RHSA-2026:95346 Released 2026-11-06 · Red Hat rating Critical
    OpenShift Container Platform 4.22.22 bug fix and security update
    • Red Hat OpenShift Container Platform 4.22 rhcos-aarch64-4.22.9.8.202611032353-0, rhcos-ppc64le-4.22.9.8.202611032353-0, rhcos-s390x-4.22.9.8.202611032353-0 +1
  • RHSA-2026:90492 Released 2026-10-26 · Red Hat rating Important
    libreswan security update
    • Red Hat Enterprise Linux AppStream (v. 8) libreswan-4.12-2.el8_10.7
  • RHSA-2026:89923 Released 2026-10-26 · Red Hat rating Important
    libreswan security update
    • Red Hat Enterprise Linux AppStream (v. 10) libreswan-5.3.3-1.el10_2, libreswan-minimal-5.3.3-1.el10_2
Show 1 more Red Hat advisories
  • RHSA-2026:89748 Released 2026-10-26 · Red Hat rating Important
    libreswan security update
    • Red Hat Enterprise Linux AppStream (v. 9) libreswan-4.15-11.el9_8

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

ProductStatusPlan or fix
Fast Datapath for RHEL 9AffectedNo fix yet
Red Hat Enterprise Linux 6AffectedNo fix planned: Out of support scope
Red Hat Enterprise Linux 7AffectedNo fix yet
Red Hat OpenShift Container Platform 4AffectedNo fix yet
Red Hat OpenShift Container Platform 5AffectedNo fix yet
Red Hat Enterprise Linux AppStream (v. 10)Fixed RHSA-2026:89923
Red Hat Enterprise Linux AppStream (v. 8)Fixed RHSA-2026:90492
Red Hat Enterprise Linux AppStream (v. 9)Fixed RHSA-2026:89748
Red Hat OpenShift Container Platform 4.22Fixed RHSA-2026:95346

Timeline

  1. 2026-10-13 Threatist record created from CVE-2026-94453
  2. 2026-10-14 Alias added: GHSA-59fc-px6w-3g8v
  3. 2026-10-14 Priority changed: MEDIUM → LOW
  4. 2026-10-16 CISA SSVC decision points changed
  5. 2026-10-26 Fix available: RHSA-2026:89748 · Red Hat
  6. 2026-10-26 Fix available: Red Hat Enterprise Linux AppStream (v. 9) · Red Hat
  7. 2026-10-26 Fix available: RHSA-2026:89923 · Red Hat
  8. 2026-10-26 Fix available: Red Hat Enterprise Linux AppStream (v. 10) · Red Hat
  9. 2026-10-27 Fix available: Red Hat Enterprise Linux AppStream (v. 8) · Red Hat
  10. 2026-10-29 Fix available: RHSA-2026:90492 · Red Hat
  11. 2026-10-30 Affected versions changed · Red Hat
  12. 2026-11-07 Fix available: RHSA-2026:95346 · Red Hat
  13. 2026-11-07 Fix available: Red Hat OpenShift Container Platform 4.22 · Red Hat

References

Patch 1

Advisory 1

  • TI-2023-09114 Libreswan 4.9 allows remote attackers to cause a denial of service (assert failure and… CVSS 3.1MEDIUM 6.5
  • TI-2013-05949 Race condition in the libreswan.spec files for Red Hat Enterprise Linux (RHEL) and Fedora… CVSS 2.0HIGH 9.3
  • TI-2023-02152 Uncontrolled resource consumption in libreswan CVSS 3.1HIGH 7.5
  • TI-2026-37395 IKEv2 Denial of Service via RSA-SHA1 (PKCS#1 RSASSA-PKCS1-v1_5) authentication payload CVSS 3.1HIGH 8.1
  • TI-2026-37394 IKEv1 Denial of Service via RSA-SHA1 (PKCS#1 Version 1.5 Encrypted) authentication payload CVSS 3.1HIGH 8.1
  • TI-2023-14401 pluto in Libreswan before 4.11 allows a denial of service (responder SPI mishandling and… CVSS 3.1HIGH 7.5
See all 28 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences