CVE-2016-5361

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.

Published: 2016-06-16 Last update: 2026-05-06 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2016-5361 is rated Moderate Risk (54/100): CVSS High severity, with medium exploitation likelihood (EPSS 1.03%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2016-5361

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2025-03-30 3.35% 1.03% -2.33%
2 2025-03-29 1.03% 3.35% +2.33%
3 2025-03-17 — 1.03% —

Full EPSS history (7 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2016-5361

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.0 HIGH
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2016-5361

OS Trackers for CVE-2016-5361

vendor priority summary link
debian unimportant CVE-2016-5361 unimportant priority: Debian including 1 source packages (libreswan), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2016-5361
redhat medium — https://access.redhat.com/security/cve/CVE-2016-5361
suse medium CVE-2016-5361 severity moderate: SUSE including 6 source package names (libreswan-3.15-8.el7, strongswan, strongswan-doc, strongswan-hmac, strongswan-ipsec, strongswan-libs0), 44 product×package rows across 16 product lines (SUSE CaaS Platform 4.0, SUSE Enterprise Storage 6, … (16 product lines)): Known Not Affected 43, Fixed 1. https://www.suse.com/security/cve/CVE-2016-5361/

Affected software / configurations for CVE-2016-5361

Vendor Product Version Raw CPE
libreswan libreswan <= 3.16 cpe:2.3:a:libreswan:libreswan:*:*:*:*:*:*:*:*

References for CVE-2016-5361

cvelogic Threat Intelligence