One-byte heap overwrite via unchecked null append
Published Mar 10, 2021 · Updated Aug 4, 2024
Out-of-bounds write in affected HHVM 4.x releases allows remote attackers to corrupt one byte beyond a full EXIF conversion buffer. The xbuf_format_converter helper used by exif_read_data writes a terminating null byte directly instead of using its capacity-aware character append routine, so a full buffer receives a one-byte write past its allocation. Reachability requires an application to pass attacker-controlled EXIF data to exif_read_data; the published record establishes memory corruption but not code execution.
Summary
What happened
Out-of-bounds write in affected HHVM 4.x releases allows remote attackers to corrupt one byte beyond a full EXIF conversion buffer. The xbuf_format_converter helper used by exif_read_data writes a terminating null byte directly instead of using its capacity-aware character append routine, so a full buffer receives a one-byte write past its allocation. Reachability requires an application to pass attacker-controlled EXIF data to exif_read_data; the published record establishes memory corruption but not code execution.
The record
- CVE
- CVE-2020-1917
- Published
- Mar 10, 2021
- Updated
- Aug 4, 2024
- Vendor
- Meta Platforms, Inc.
- Product
- HHVM
- Classifications
- CWE-787, CWE-122, T1190
- 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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