# CVE-2026-78124: strongSwan openssl plugin memory leak in PKCS#7 certificate enumeration

Source: https://junglewise.ai/threats/cve-2026-78124-strongswan-openssl-plugin-memory-leak-in-pkcs-7-certificate  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-11. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-78124 · Severity: low · CVSS 3.7 · Published 2026-09-11

strongSwan is a widely-used VPN and IPsec implementation that processes X.509 certificates for authentication. A memory leak in its PKCS#7 certificate handling can be triggered by sending specially crafted certificate containers in IKEv1 connections, allowing attackers to exhaust server memory and cause service disruption without requiring authentication.

Technologies: [strongSwan](https://junglewise.ai/threats/technologies/strongswan). Vendors: [strongSwan](https://junglewise.ai/threats/vendors/strongswan).

## Quick answers

**Is CVE-2026-78124 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-78124 being exploited in the wild.

**How severe is CVE-2026-78124?** Low severity, with a CVSS score of 3.7, published 11 September 2026.

**Which products and versions are affected?** strongSwan 5.0.2 through 6.0.7.

**Is there a fix for CVE-2026-78124?** A patch was published on 2026-09-07: Fixed in version 6.1.0 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-78124 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-78124?** Check whether you run strongSwan at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The openssl plugin in strongSwan contains a memory leak in its PKCS#7/CMS container handling. When enumerating certificates using CMS_get1_certs(), the refcount is increased for the stack and contained X.509 structures, but the enumerator destructor fails to call sk_X509_pop_free() to release that refcount, leading to memory leaks per certificate processed. The vulnerability is reachable pre-authentication via IKEv1 certificate payloads using PKCS#7 wrapped X.509 encoding; attackers can trigger leaks with crafted containers requiring at least two IKEv1 messages. The issue affects strongSwan 5.0.2 through 6.0.7 and is fixed in version 6.1.0.

## Affected products

- strongSwan strongSwan 5.0.2 through 6.0.7

## Timeline

- 2026-09-07: disclosed
- 2026-09-07: patched: Fixed in version 6.1.0

## References

- [https://github.com/strongswan/strongswan/releases/tag/6.1.0](https://github.com/strongswan/strongswan/releases/tag/6.1.0)
- [https://www.strongswan.org/blog/2026/09/07/strongswan-vulnerability-(cve-2026-78124).html](https://www.strongswan.org/blog/2026/09/07/strongswan-vulnerability-(cve-2026-78124).html)

## Related threats

- [strongSwan libcharon authentication bypass in IKEv2 CREATE_CHILD_SA handling](https://junglewise.ai/threats/cve-2026-78135-strongswan-libcharon-authentication-bypass-in-ikev2-create-child)
- [strongSwan incorrect identity binding in EAP-PEAP and EAP-TTLS](https://junglewise.ai/threats/cve-2026-78134-strongswan-incorrect-identity-binding-in-eap-peap-and-eap-ttls)
- [strongSwan libcharon use-after-free in IKEv2 rekeying collision handling](https://junglewise.ai/threats/cve-2026-78133-strongswan-libcharon-use-after-free-in-ikev2-rekeying-collision)
- [strongSwan x509 plugin infinite loop in ietfAttrSyntax parsing](https://junglewise.ai/threats/cve-2026-78132-strongswan-x509-plugin-infinite-loop-in-ietfattrsyntax-parsing)
- [strongSwan x509 plugin memory leak in attribute certificate parsing](https://junglewise.ai/threats/cve-2026-78131-strongswan-x509-plugin-memory-leak-in-attribute-certificate)