Description
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.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 7 | libreswan | 3.15-8.el7 | RHSA-2016:2603 |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 7 | libreswan | 3.15-8.0.1.el7 | ELSA-2016-2603 |
Advisories 2
- RHSA-2016:2603 Red Hat Security Advisory: libreswan security and bug fix update Red Hat Security Advisories (RHSA) · Jun 26, 2026
- ELSA-2016-2603 Moderate: libreswan security and bug fix update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Nov 9, 2016
References
- [swan-dev] 20160313 Proposal: Do not retransmit IKEv1 reply for initial responder states mailing-list
- RHSA-2016:2603 vendor-advisory
- https://github.com/libreswan/libreswan/commit/152d6d95632d8b9477c170f1de99bcd86d7fb1d6
- [oss-security] 20160610 Re: CVE Request: IKEv1 protocol is vulnerable to DoS amplification attack mailing-list