Out-of-bounds read via unchecked font offset
Published Jan 8, 2020 · Updated Aug 4, 2024
Out-of-bounds read in stb_truetype.h through 1.22 allows context-dependent attackers to read past heap data via a crafted font. The ttUSHORT function reads two bytes from a caller-supplied font pointer without checking that both bytes remain inside the allocated font buffer. Reachability depends on an application passing attacker-controlled font data to stbtt_InitFont; the published proof demonstrates an invalid read and process abort under AddressSanitizer, not data disclosure.
Summary
What happened
Out-of-bounds read in stb_truetype.h through 1.22 allows context-dependent attackers to read past heap data via a crafted font. The ttUSHORT function reads two bytes from a caller-supplied font pointer without checking that both bytes remain inside the allocated font buffer. Reachability depends on an application passing attacker-controlled font data to stbtt_InitFont; the published proof demonstrates an invalid read and process abort under AddressSanitizer, not data disclosure.
The record
- CVE
- CVE-2020-6621
- Published
- Jan 8, 2020
- Updated
- Aug 4, 2024
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- T1204.002
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jan 8, 2020CVE 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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What is affected?
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Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
- Upstream issue 867 proof-of-concept fontproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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