Service interruption via reference-table hash collisions
Published Oct 21, 2021 · Updated Aug 4, 2024
Algorithmic complexity flaws in Reddit Snudown before 1.7.0 allow remote authenticated users to interrupt services with crafted Markdown. The reference table uses predictable SDBM hashes, permits duplicate labels, and traverses attacker-expanded collision lists during lookups. Exploitation requires a service that passes attacker-controlled Markdown to Snudown, where repeated parsing consumes excessive processing time and degrades availability.
Summary
What happened
Algorithmic complexity flaws in Reddit Snudown before 1.7.0 allow remote authenticated users to interrupt services with crafted Markdown. The reference table uses predictable SDBM hashes, permits duplicate labels, and traverses attacker-expanded collision lists during lookups. Exploitation requires a service that passes attacker-controlled Markdown to Snudown, where repeated parsing consumes excessive processing time and degrades availability.
The record
- CVE
- CVE-2021-41168
- Published
- Oct 21, 2021
- Updated
- Aug 4, 2024
- Vendor
- Product
- Snudown
- Classifications
- CWE-20, CWE-327, CWE-400, T1499.003
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Oct 21, 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=< 1.7.0
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
- Reference-table collision proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
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