CVE-2026-76838 HiEventsDev CVE debrief

Who should care

Defenders responsible for Hi.Events deployments, especially those using event or organizer webhooks, should assess exposure to this vulnerability and prioritize verification and remediation efforts.

Why it matters

CVE-2026-76838 is a high-severity vulnerability in Hi.Events that allows for server-side request forgery (SSRF) via unvalidated webhook redirects. Defenders responsible for Hi.Events deployments, especially those using event or organizer webhooks, should assess exposure and prioritize verification and remediation efforts to prevent potential SSRF attacks.

• Potential SSRF attacks may lead to unauthorized requests to internal services.
• Attackers may exploit this vulnerability to access sensitive information or disrupt service operations.
• Defenders must verify exposure and implement compensating controls to prevent exploitation.
• Remediation priority is high due to the potential for significant impact.

Technical summary

The Hi.Events application does not revalidate a webhook destination at dispatch time, allowing an attacker to cause the server to make unintended requests by exploiting the lack of validation on redirects. This issue was addressed in version 1.11.1-beta, which revalidates the destination at dispatch, pins the validated address, checks every redirect hop, and decodes IPv6 transition addresses that previously bypassed the filter. Defenders should prioritize verifying exposure to this vulnerability, especially if using Hi.Events for event or organizer webhooks, and take immediate action to prevent potential SSRF attacks.

Defensive priority

Defenders should prioritize verifying exposure to this vulnerability, especially if using Hi.Events for event or organizer webhooks. Immediate action is required to prevent potential SSRF attacks.

Recommended defensive actions

• Verify if using Hi.Events for event or organizer webhooks and assess exposure to this vulnerability.
• Check if the version is prior to 1.11.1-beta and update to the latest version if necessary.
• Monitor webhook logs for suspicious requests.
• Implement additional security measures to detect and prevent SSRF attacks.
• Review compensating controls for exposed systems while remediation is scheduled and verified.
• Track exceptions, retest remediated assets, and close the item only after evidence is documented.
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.

Evidence notes

The CVE record and source references provide details on the vulnerability, including the affected code and the fix in version 1.11.1-beta. However, the exact scope of affected versions and deployments is not specified.

Sources and 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.