CVE-2023-37467Network attack vector

XSS protection bypass via cached CSP nonce

Published Jul 28, 2023 · Updated Oct 10, 2024

CSP bypass in Discourse 3.1.0.beta1 through 3.1.0.beta6 allows remote authenticated users to run scripts in anonymous visitors' browsers. The anonymous-page cache stores a response whose Google Tag Manager markup and script-src directive contain one request nonce, then serves that nonce again. Google Tag Manager and CSP must be enabled, and exploitation also requires a separate XSS vector; the vendor reported none, and logged-in responses are unaffected.

CVSS severity6.8
Medium
EPSS probability0.36%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

CSP bypass in Discourse 3.1.0.beta1 through 3.1.0.beta6 allows remote authenticated users to run scripts in anonymous visitors' browsers. The anonymous-page cache stores a response whose Google Tag Manager markup and script-src directive contain one request nonce, then serves that nonce again. Google Tag Manager and CSP must be enabled, and exploitation also requires a separate XSS vector; the vendor reported none, and logged-in responses are unaffected.

The record

CVE
CVE-2023-37467
Published
Jul 28, 2023
Updated
Oct 10, 2024
Vendor
Discourse
Product
Discourse
Classifications
CWE-79, CWE-323
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 28, 2023CVE publishedPublication date reported by the CVE source.
  2. Oct 10, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 3.1.0.beta1, < 3.1.0.beta7
  2. Affected versionversion=3.1.0.beta1 <3.1.0.beta7

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Discourse · Discourseversion=>= 3.1.0.beta1, < 3.1.0.beta7; version=3.1.0.beta1 <3.1.0.beta7

Published CVSS scores

6.8GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-323Reusing a Nonce, Key Pair in Encryption

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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