Discourse up to 2026.1.7/2026.6.2/2026.7.1 Iframe input validation

CVSS Meta Temp Score
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CTI Interest Score
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4.2$0-$5k0.11+

Summaryinfo

A vulnerability was found in Discourse up to 2026.1.7/2026.6.2/2026.7.1 and classified as problematic. This issue affects some unknown processing of the component Iframe Handler. The manipulation results in input validation. This vulnerability is cataloged as CVE-2026-91132. The attack may be launched remotely. There is no exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic has been found in Discourse up to 2026.1.7/2026.6.2/2026.7.1. Affected is an unknown code of the component Iframe Handler. The manipulation with an unknown input leads to a input validation vulnerability. CWE is classifying the issue as CWE-20. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. This is going to have an impact on integrity. CVE summarizes:

Discourse is an open-source discussion platform. Prior to 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0, sites using wildcard patterns in the allowed_iframes setting could accept a crafted iframe URL whose allowlisted suffix appeared after a URL authority separator. The wildcard origin check matched the allowed domain text, while browser URL parsing selected a different attacker-controlled origin. A user with posting privileges could exploit the flaw through a post or a Onebox oEmbed response and cause an attacker-controlled iframe to be rendered independently of the allowlisted domain. Successful exploitation requires a site-configured wildcard iframe pattern and the ability to create a post or trigger an oEmbed request for an attacker-controlled URL. This issue is fixed in versions 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-91132 since 09/14/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. There are neither technical details nor an exploit publicly available.

Upgrading to version 2026.1.8, 2026.6.3, 2026.7.2 or 2026.8.0 eliminates this vulnerability.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.3
VulDB Meta Temp Score: 4.2

VulDB Base Score: 4.3
VulDB Temp Score: 4.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 4.3
CNA Vector (GitHub_M): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Input validation
CWE: CWE-20
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Discourse 2026.1.8/2026.6.3/2026.7.2/2026.8.0

Timelineinfo

09/14/2026 CVE reserved
09/24/2026 +10 days Advisory disclosed
09/24/2026 +0 days VulDB entry created
09/24/2026 +0 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: github.com
Status: Confirmed

CVE: CVE-2026-91132 (🔒)
GCVE (CVE): GCVE-0-2026-91132
GCVE (VulDB): GCVE-100-409644

Entryinfo

Created: 09/24/2026 19:53
Changes: 09/24/2026 19:53 (64)
Complete: 🔍
Cache ID: 216::103

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Discussion

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