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Fencer Intel
high 7.5

CVE-2016-5361 json

programs/pluto/ikev1.c in libreswan before 3.17 retransmits in initial-responder states, which allows remote attackers to cause a denial of…

published 2016-06-16 10 y ago modified 2026-06-17 4 mo ago also EUVD-2016-6312

cvss
7.5
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.7%
EPSS 2.7% chance of exploitation in 30 days, percentile 86%
public exploits
0
none known

Summary

programs/pluto/ikev1.c in libreswan before 3.17 retransmits in initial-responder states, which allows remote attackers to cause a denial of service (traffic amplification) via a spoofed UDP packet. NOTE: the original behavior complies with the IKEv1 protocol, but has a required security update from the libreswan vendor; as of 2016-06-10, it is expected that several other IKEv1 implementations will have vendor-required security updates, with separate CVE IDs assigned to each.

Patch / fix

  • libreswan RHEL 7 3.15-8.el7

red hat advisories RHSA-2016:2603

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2016-5361 updated cvss 5.0

IKEv1 protocol is vulnerable to DoS amplification attack

  • Red Hat Enterprise Linux 5 openswan, ipsec-tools Red Hat Enterprise Linux 6 openswan, libreswan
    affected: no fix planned “Will not fix”
  • Red Hat Enterprise Linux Client (v. 7) libreswan 3.15-8.el7 Red Hat Enterprise Linux Server (v. 7) libreswan 3.15-8.el7 Red Hat Enterprise Linux Workstation (v. 7) libreswan 3.15-8.el7
    fixed: vendor fix RHSA-2016:2603

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

2.72% chance of exploitation in the next 30 days, higher than 86% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.0 7.5 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P

Classification

Weakness
  • CWE-20 Improper Input Validation

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.