Discourse up to 2026.1.1/2026.2.0/2026.3.0-latest Content Security Policy cross site scripting

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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4.1$0-$5k0.00

Summaryinfo

A vulnerability has been found in Discourse up to 2026.1.1/2026.2.0/2026.3.0-latest and classified as problematic. This vulnerability affects unknown code of the component Content Security Policy Handler. The manipulation leads to cross site scripting. This vulnerability is listed as CVE-2026-33395. The attack may be initiated remotely. There is no available exploit. The affected component should be upgraded.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in Discourse up to 2026.1.1/2026.2.0/2026.3.0-latest. This issue affects an unknown part of the component Content Security Policy Handler. The manipulation with an unknown input leads to a cross site scripting vulnerability. Using CWE to declare the problem leads to CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. Impacted is integrity. The summary by CVE is:

Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, the discourse-graphviz plugin contains a stored cross-site scripting (XSS) vulnerability that allows authenticated users to inject malicious JavaScript code through DOT graph definitions. For instances with CSP disabled only. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. As a workaround, disable the graphviz plugin, upgrade to a patched version, or enable a content security policy.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-33395 since 03/19/2026. The exploitation is known to be difficult. The attack may be initiated remotely. It demands that the victim is doing some kind of user interaction. Neither technical details nor an exploit are publicly available. MITRE ATT&CK project uses the attack technique T1059.007 for this issue.

Upgrading to version 2026.1.2 or 2026.2.1 eliminates this vulnerability. Applying the patch 0471e68ed0b594bf386e068f228849244b880ef1 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.1
VulDB Meta Temp Score: 4.1

VulDB Base Score: 2.6
VulDB Temp Score: 2.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 5.4
NVD Vector: 🔒

CNA Base Score: 4.4
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: Cross site scripting
CWE: CWE-79 / CWE-94 / CWE-74
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

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 2026.1.2/2026.2.1
Patch: 0471e68ed0b594bf386e068f228849244b880ef1

Timelineinfo

03/19/2026 CVE reserved
03/20/2026 +1 days Advisory disclosed
03/20/2026 +0 days VulDB entry created
03/25/2026 +5 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: GHSA-23c7-gq89-xm5v
Status: Confirmed

CVE: CVE-2026-33395 (🔒)
GCVE (CVE): GCVE-0-2026-33395
GCVE (VulDB): GCVE-100-351893

Entryinfo

Created: 03/20/2026 07:56
Updated: 03/25/2026 08:33
Changes: 03/20/2026 07:56 (67), 03/23/2026 00:51 (1), 03/25/2026 08:33 (11)
Complete: 🔍
Cache ID: 216::103

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