CVE-2024-3652VulnerabilityPublished 11 Apr 2024Updated 27 Feb 2026

CVE-2024-3652: IKEv1 with default AH/ESP configuration can cause libreswan to abort and restart

Affects libreswanSource CVE Database V5

Not known to be exploited · CVSS 6.5 Medium.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 3.1 base score

6.5Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.8% chance of exploitation in 30 days – higher than 56% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: Low
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 11 Apr 2024
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-26.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
The Libreswan Project (www.libreswan.org) libreswan	Affected =3.22	Fixed in–

AI-suggested

To mitigate CVE-2024-3652, organizations should first audit their Libreswan deployments to identify usage of version 3.22 and reliance on IKEv1 with default AH/ESP configurations. Where possible, explicitly specify the esp= line in IKEv1 configurations to avoid triggering the default proposal handler that causes the crash. Transitioning VPN configurations from IKEv1 to IKEv2 is strongly recommended, as IKEv2 is not affected by this vulnerability and offers improved security and stability. Monitor Libreswan project communications for forthcoming patches or updates addressing this issue and apply them promptly once available. In the interim, consider implementing network-level controls to restrict or monitor IKEv1 negotiation attempts from untrusted sources to reduce exposure. Additionally, configure robust logging and alerting on Libreswan service restarts to detect potential exploitation attempts. For critical environments, deploying redundant VPN gateways or failover mechanisms can help maintain availability during potential disruptions. Avoid using AES-GMAC in IKEv1 proposals until a fix is released or the configuration is hardened.

Description

The Libreswan Project was notified of an issue causing libreswan to restart when using IKEv1 without specifying an esp= line. When the peer requests AES-GMAC, libreswan's default proposal handler causes an assertion failure and crashes and restarts. IKEv2 connections are not affected.

Impact

The primary impact of CVE-2024-3652 is on the availability of VPN services using Libreswan with IKEv1 configurations. Organizations relying on Libreswan 3.22 for secure IPsec tunnels may experience unexpected service interruptions due to the process abort and restart triggered by the vulnerability. This can lead to denial of service conditions, disrupting secure communications, remote access, and site-to-site VPN connectivity. Although confidentiality and integrity of data are not directly compromised, the loss of VPN availability can affect business operations, especially for organizations dependent on continuous secure network access. The vulnerability requires an attacker to initiate IKEv1 negotiations with a specially crafted proposal requesting AES-GMAC, which is feasible for network-level adversaries with some privileges. The lack of impact on IKEv2 reduces the overall risk for environments that have migrated to newer protocols. However, legacy systems and configurations still using IKEv1 are at risk. The absence of known exploits limits immediate widespread impact, but the vulnerability could be leveraged for targeted denial of service attacks against critical infrastructure, government networks, and enterprises using Libreswan-based VPNs.

CWE-404Improper Resource Shutdown or Release (opens in a new tab)
Class weaknessLikelihood of exploit: Medium
The product does not release or incorrectly releases a resource before it is made available for re-use.
Requirements · Language Selection
Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Implementation
It is good practice to be responsible for freeing all resources you allocate and to be consistent with how and where you free memory in a function. If you allocate memory that you intend to free upon completion of the function, you must be sure to free the memory at all exit points for that function including error…
Implementation
Memory should be allocated/freed using matching functions such as malloc/free, new/delete, and new[]/delete[].
Attack patterns
TCP Fragmentation (opens in a new tab)
UDP Fragmentation (opens in a new tab)
ICMP Fragmentation (opens in a new tab)
BlueSmacking (opens in a new tab)
Flooding (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 27 Feb 2026, 15:42 UTC

WeaknessesCWE-404

Technical details

References

Community reviews

Related threats