Partial denial of service via cacheable error responses
Published Dec 1, 2021 · Updated Aug 4, 2024
Cache poisoning in Discourse stable before 2.7.11 and beta or tests-passed before 2.8.0.beta9 allows remote attackers to disrupt pages. The anonymous-cache and public-exception middleware return attacker-triggered 400 or 413 errors without controls preventing shared caching, so intermediaries can store them. No authentication is required; anonymous visitors then receive a cached error body instead of the requested HTML page, causing a partial service interruption.
Summary
What happened
Cache poisoning in Discourse stable before 2.7.11 and beta or tests-passed before 2.8.0.beta9 allows remote attackers to disrupt pages. The anonymous-cache and public-exception middleware return attacker-triggered 400 or 413 errors without controls preventing shared caching, so intermediaries can store them. No authentication is required; anonymous visitors then receive a cached error body instead of the requested HTML page, causing a partial service interruption.
The record
- CVE
- CVE-2021-43794
- Published
- Dec 1, 2021
- Updated
- Aug 4, 2024
- Vendor
- Discourse
- Product
- Discourse
- Classifications
- CWE-610, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Dec 1, 2021CVE publishedPublication date reported by the CVE source.
- Aug 4, 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 < 2.8.0.beta9
- Affected versionversion=stable < 2.7.11
- Affected versionversion=tests-passed < 2.8.0.beta9
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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