CVE-2026-72720

Discourse: HTML injection in PrettyText.format_for_email from cooked-attribute reparsing

MEDIUM
6.4
CVSS Score
Published: August 10, 2026 at 03:41 PM UTC
Updated: September 8, 2026 at 09:09 PM UTC
1 product affected across 1 vendorDiscourse

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Severity
MEDIUM6.4
Exploit prediction
EPSS 0.4%
SSVC
No known exploit

Description

Discourse is an open-source discussion platform. Prior to 2026.1.7, 2026.6.2, 2026.7.1, and 2026.8.0-latest.1, Discourse has HTML injection in PrettyText.format_for_email because cooked attribute values are reparsed as markup. Crafted Vimeo iframe sources, secure-upload URLs or dimensions, and hashtag data-slug values can cause decoded attribute text to be reinterpreted as HTML. The vulnerable conversion also fails to strictly validate the Vimeo iframe host and path, allowing non-Vimeo allowlisted iframes to be converted. This issue is fixed in versions 2026.1.7, 2026.6.2, 2026.7.1, and 2026.8.0-latest.1.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 2026.1.7v < 2026.6.2v < 2026.7.1v < 2026.8.0-latest.1
Affected range stops below 2026.1.7, so it looks safe — our inference, not a vendor statement
Affected range stops below 2026.6.2, so it looks safe — our inference, not a vendor statement
Affected range stops below 2026.7.1, so it looks safe — our inference, not a vendor statement
Affected range stops below 2026.8.0-latest.1, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

6.4MEDIUMGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
CHANGED
Confidentiality
LOW
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-79

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