Service interruption via unchecked salt-length terminator
Published Mar 10, 2021 · Updated Aug 4, 2024
Out-of-bounds write in HHVM crypt() in affected releases through 4.98.0 allows remote attackers to interrupt service. The crypt implementation writes a null byte at an offset derived from the untrusted salt length without confirming that the offset remains inside its stack buffer. Unauthenticated network reachability requires an application path that passes attacker-controlled salt data to crypt(); the reported consequence is availability loss, not data disclosure or modification.
Summary
What happened
Out-of-bounds write in HHVM crypt() in affected releases through 4.98.0 allows remote attackers to interrupt service. The crypt implementation writes a null byte at an offset derived from the untrusted salt length without confirming that the offset remains inside its stack buffer. Unauthenticated network reachability requires an application path that passes attacker-controlled salt data to crypt(); the reported consequence is availability loss, not data disclosure or modification.
The record
- CVE
- CVE-2020-1921
- Published
- Mar 10, 2021
- Updated
- Aug 4, 2024
- Vendor
- Meta Platforms, Inc.
- Product
- HHVM
- Classifications
- CWE-121, CWE-787, T1499
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Mar 10, 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=4.57.0 <unspecified
- Affected versionversion=4.81.0 <unspecified
- Affected versionversion=4.94.0
- Affected versionversion=4.95.0
- Affected versionversion=4.96.0
- Affected versionversion=4.97.0
- Affected versionversion=4.98.0
- Affected versionversion=unspecified <4.56.3
What conditions does exploitation require?
What is affected?
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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