# CVE-2026-78123: strongSwan openssl plugin expired pointer dereference in PKCS#7 parsing

Source: https://junglewise.ai/threats/cve-2026-78123-strongswan-openssl-plugin-expired-pointer-dereference-in-pkcs-7  
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-2026-78123 · Severity: medium · CVSS 5.9 · Published 2026-09-11

strongSwan is an open-source IPsec implementation used to establish secure VPN tunnels and encrypted communications. A flaw in the openssl plugin's handling of PKCS#7 certificate containers can cause the service to crash when processing specially crafted PKCS#7 structures. An attacker could exploit this to disrupt VPN connectivity and authentication services.

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

## Quick answers

**Is CVE-2026-78123 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-78123 being exploited in the wild.

**How severe is CVE-2026-78123?** Medium severity, with a CVSS score of 5.9, published 11 September 2026.

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

**Is there a fix for CVE-2026-78123?** A patch was published on 2026-09-07: Fixed in strongSwan 6.1.0 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-78123 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-78123?** 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 does not properly initialize stack variables when parsing PKCS#7 signerInfo or recipientInfo structures that use subjectKeyIdentifier encoding instead of issuerAndSerialNumber. When the OpenSSL library function CMS_SignerInfo_get0_signer_id() or CMS_RecipientInfo_ktri_get0_signer_id() encounters subjectKeyIdentifier format, it leaves uninitialized pointers unchanged despite returning success. Subsequent code dereferences these uninitialized pointers via openssl_x509_name2id() and openssl_asn1_str2chunk(), causing a segmentation fault. The vulnerability affects strongSwan 5.0.2 through 6.0.7 and is reachable via IKEv1 connections. Remote code execution is unlikely; the primary impact is denial of service through a crash.

## Affected products

- strongSwan strongSwan 5.0.2 through 6.0.7

## Timeline

- 2026-09-07: disclosed
- 2026-09-07: patched: Fixed in strongSwan 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-2026-78123).html](https://www.strongswan.org/blog/2026/09/07/strongswan-vulnerability-(cve-2026-78123).html)

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- [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)