XSS defense bypass via reused CSP nonce
Published Jul 13, 2023 · Updated Oct 21, 2024
CSP nonce reuse in Discourse stable 3.0.4 and earlier allows remote authenticated users to bypass XSS protections via network requests. When Google Tag Manager is enabled, Discourse reuses the same CSP nonce across responses instead of creating a fresh per-response value. Exploitation requires a separate XSS vector; none is known, but successful abuse executes attacker-controlled script despite the policy.
Summary
What happened
CSP nonce reuse in Discourse stable 3.0.4 and earlier allows remote authenticated users to bypass XSS protections via network requests. When Google Tag Manager is enabled, Discourse reuses the same CSP nonce across responses instead of creating a fresh per-response value. Exploitation requires a separate XSS vector; none is known, but successful abuse executes attacker-controlled script despite the policy.
The record
- CVE
- CVE-2023-36473
- Published
- Jul 13, 2023
- Updated
- Oct 21, 2024
- Vendor
- Discourse
- Product
- Discourse
- Classifications
- CWE-79
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Jul 13, 2023CVE publishedPublication date reported by the CVE source.
- Oct 21, 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.
- Affected versionversion=beta >= 3.1.0.beta6
- Affected versionversion=stable >= 3.0.5
- Affected versionversion=tests-passed >= 3.1.0.beta6
What conditions does exploitation require?
What is affected?
Published CVSS scores
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.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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