Denial of service via unterminated varint parsing
Published Apr 28, 2021 · Updated Aug 3, 2024
Infinite-loop denial of service in github.com/ulikunitz/xz before 0.5.8 allows attackers to hang decompression with crafted xz data. The readUvarint parser consumes continuation bytes without enforcing the 10-byte maximum for a 64-bit unsigned integer, so a malicious sequence never terminates its loop. Any application that passes attacker-controlled xz streams to Reader.Read can consume a worker indefinitely; exposure depends on how that application accepts compressed input.
Summary
What happened
Infinite-loop denial of service in github.com/ulikunitz/xz before 0.5.8 allows attackers to hang decompression with crafted xz data. The readUvarint parser consumes continuation bytes without enforcing the 10-byte maximum for a 64-bit unsigned integer, so a malicious sequence never terminates its loop. Any application that passes attacker-controlled xz streams to Reader.Read can consume a worker indefinitely; exposure depends on how that application accepts compressed input.
The record
- CVE
- CVE-2021-29482
- Published
- Apr 28, 2021
- Updated
- Aug 3, 2024
- Vendor
- Ulrich Kunitz
- Product
- github.com/ulikunitz/xz
- Classifications
- T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Apr 28, 2021CVE publishedPublication date reported by the CVE source.
- Aug 3, 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=< 0.5.8
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
- Upstream readUvarint regression testproof of concept · demonstrated
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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