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CVE-2026-91134 Details

ANALYZED

This CVE record has been analyzed and enriched by NVDAPI.com as an independent party.

Description

Discourse is an open-source discussion platform. Prior to 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0, the Discourse post sanitizer allowed a stored cross-origin iframe to bypass the allowed_iframes prefix policy when the iframe src contained encoded userinfo. The sanitizer validated a decoded form differently from the stored iframe src, allowing the browser to interpret an attacker-controlled host while the allowlist check accepted the encoded URL as an allowed prefix. An authenticated user with posting privileges could persist the iframe in a post and cause attacker-controlled cross-origin content to be rendered. This issue is fixed in versions 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0.

Metrics

CVSS 3.x Severity and Vector Strings:

VolerionCVSS-B:5 MEDIUMVector:CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:N

CNA: [email protected]CVSS-B:5.4 MEDIUMVector:CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

References to Advisories, Solutions, and Tools

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URL	Source(s)	Tag(s)
https://github.com/discourse/discourse/commit/0a8015e6c7a5079981843721494d30c9a91f5415	[email protected]	Source CodeVendor
https://github.com/discourse/discourse/commit/1304b0c04f87534053b0d574ae5a9b9ba13dd590	[email protected]	Source CodeVendor
https://github.com/discourse/discourse/commit/bac7dd1201911851462483271b4567246fa1309d	[email protected]	Source CodeVendor
https://github.com/discourse/discourse/commit/fed3a58c48412ce7207b72a4629ddbc44482cd64	[email protected]	Source CodeVendor
https://github.com/discourse/discourse/pull/42882	[email protected]	Issue TrackingVendor
https://github.com/discourse/discourse/security/advisories/GHSA-54vw-chv3-wjpv	[email protected]	AdvisoryRemedyVendor

see all 6 references

Weakness Enumeration

CWE-ID	CWE Name	Source
CWE-20	Improper Input Validation	[email protected]

Affected Products

Product	Versions
Discourse	>= 2026.1.0-latest (semver) >= 2026.6.0-latest (semver) >= 2026.7.0-latest (semver)
CPE cpe:2.3:a:discourse:discourse:::::::: Remediation Upgrade: 2026.1.8moderate effort Upgrade: 2026.6.3moderate effort Upgrade: 2026.7.2moderate effort Upgrade: 2026.8.0moderate effort

Change History

1 change record found show changes