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PatchSiren cyber security CVE debrief

CVE-2026-78123 strongSwan CVE debrief

A vulnerability in strongSwan versions 5.0.2 through 6.0.7 allows for an expired pointer dereference in PKCS#7 parsing within the openssl plugin, potentially leading to a denial of service. This medium-severity issue, with a CVSS score of 5.9, was publicly disclosed on September 11, 2026. The vulnerability affects strongSwan IKE daemon deployments using the openssl plugin. Verification of strongSwan version and openssl plugin usage is necessary to determine exposure. Potential denial of service impact requires assessment and mitigation planning. Remediation or compensating controls may be necessary for vulnerable deployments. Monitoring for official vendor updates or patches is a

Vendor
strongSwan
Product
Unknown
CVSS
MEDIUM 5.9
CISA KEV
Not listed in stored evidence
Original CVE published
2026-09-11
Original CVE updated
2026-09-11
Advisory published
2026-09-11
Advisory updated
2026-09-11

Who should care

Defenders responsible for strongSwan deployments, especially those using the openssl plugin, should assess their exposure to this vulnerability and prioritize verification and potential remediation efforts.

Why it matters

CVE-2026-78123 is a medium-severity vulnerability in strongSwan versions 5.0.2 through 6.0.7, potentially leading to denial of service. Defenders should verify exposure, assess impact, and prioritize remediation or compensating controls.

  • Verification of strongSwan version and openssl plugin usage is necessary to determine exposure.
  • Potential denial of service impact requires assessment and mitigation planning.
  • Remediation or compensating controls may be necessary for vulnerable deployments.
  • Monitoring for official vendor updates or patches is crucial for affected systems.

Technical summary

The strongSwan IKE daemon, versions 5.0.2 through 6.0.7, contains a vulnerability in the openssl plugin that allows for an expired pointer dereference during PKCS#7 parsing. This issue can potentially lead to a denial of service. The vulnerability has been publicly disclosed and has a CVSS score of 5.9, indicating a medium level of severity.

Defensive priority

Defenders should prioritize verifying exposure in strongSwan deployments, especially those using the openssl plugin, and assess the need for updates or compensating controls.

Recommended defensive actions

  • Verify strongSwan version and openssl plugin usage
  • Assess exposure and potential impact on systems
  • Monitor for official vendor remediation or updates
  • Consider compensating controls for vulnerable deployments

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, but additional information on potential exploitation or affected systems is limited.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-78123 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-78123

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-78123 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-78123

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.