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CVE-2026-58487 hedgedoc CVE debrief

CVE-2026-58487 is a stored HTML injection vulnerability in HedgeDoc, a real-time, collaborative, markdown notes application. The vulnerability was caused by the unsafe handling of the local-part of registered email addresses. An attacker could register a specially crafted email address and inject arbitrary HTML into pages viewed by other users. The vulnerability has a CVSS score of 5.1 and a severity of MEDIUM. Users of HedgeDoc versions prior to 1.11.0 should apply the patch to prevent stored HTML injection attacks.

Vendor
hedgedoc
Product
Unknown
CVSS
MEDIUM 5.1
CISA KEV
Not listed in stored evidence
Original CVE published
2026-07-13
Original CVE updated
2026-07-13
Advisory published
2026-07-13
Advisory updated
2026-07-13

Who should care

Users of HedgeDoc versions prior to 1.11.0 should apply the patch to prevent stored HTML injection attacks. Operators of HedgeDoc instances should review user email addresses to prevent similar vulnerabilities. Security teams should monitor for suspicious activity on the HedgeDoc application. Platform administrators should ensure that the patch is applied to all affected systems.

Technical summary

HedgeDoc accepted RFC 5321 quoted-string local-parts in email addresses during registration. The local-part was then reused as the user's display name without escaping and rendered into HTML in multiple places, including publish and slide views as well as the collaborative editor. An attacker could break out of an HTML attribute and inject arbitrary markup into the page. The deployed Content-Security-Policy prevented straightforward inline JavaScript execution, but the injected HTML was still sufficient to alter page content and embed attacker-controlled resources such as cross-origin iframes.

Defensive priority

Medium

Recommended defensive actions

  • Apply the patch to upgrade to HedgeDoc version 1.11.0 or later
  • Review and update user email addresses to prevent similar vulnerabilities
  • Monitor for suspicious activity on the HedgeDoc application
  • Review compensating controls for exposed systems while remediation is scheduled and verified
  • Check relevant monitoring, detection, and logs for exposed assets that need extra review
  • 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 was published on 2026-07-13T22:16:48.410Z and has not been modified since then. The NVD entry is currently 5.1 MEDIUM. There is limited information available about the vulnerability, and defenders should verify the affected scope and severity with the vendor. The vulnerability affects HedgeDoc versions prior to 1.11.0.

Official resources

AI-assisted PatchSiren debrief based on the supplied source corpus. The CVE record was published on 2026-07-13T22:16:48.410Z and has not been modified since then.