CVE-2021-21259
In HedgeDoc before version 1.7.2, an attacker can inject arbitrary JavaScript into a HedgeDoc note, which is executed when the note is viewed in slide mode.
Does this matter?
Lower severity and a low EPSS score (1.37%). Track it; it rarely justifies an emergency change on its own.
Description
HedgeDoc is open source software which lets you create real-time collaborative markdown notes. In HedgeDoc before version 1.7.2, an attacker can inject arbitrary JavaScript into a HedgeDoc note, which is executed when the note is viewed in slide mode. Depending on the configuration of the instance, the attacker may not need authentication to create or edit notes. The problem is patched in HedgeDoc 1.7.2. As a workaround, disallow loading JavaScript from 3rd party sites using the `Content-Security-Policy` header. Note that this will break some embedded content.
- CVSS 3.1
- 6.1 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
- EPSS
- 1.37% probability · 72th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-79
- Affected
- hedgedoc/hedgedoc
- Source
- security-advisories@github.com
EPSS 1.4% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://github.com/hackmdio/codimd/issues/1648Exploit, Patch, Third Party Advisory
- https://github.com/hedgedoc/hedgedoc/commit/35b0d39a12aa35f27fba8c1f50b1886706e7efefPatch, Third Party Advisory
- https://github.com/hedgedoc/hedgedoc/releases/tag/1.7.2Release Notes, Third Party Advisory
- https://github.com/hedgedoc/hedgedoc/security/advisories/GHSA-44w9-vm8p-3cxwThird Party Advisory
- https://github.com/hackmdio/codimd/issues/1648Exploit, Patch, Third Party Advisory
- https://github.com/hedgedoc/hedgedoc/commit/35b0d39a12aa35f27fba8c1f50b1886706e7efefPatch, Third Party Advisory
- https://github.com/hedgedoc/hedgedoc/releases/tag/1.7.2Release Notes, Third Party Advisory
- https://github.com/hedgedoc/hedgedoc/security/advisories/GHSA-44w9-vm8p-3cxwThird Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.