Application crash via malformed CFF font parsing
Published Apr 1, 2026 · Updated Apr 1, 2026
Out-of-bounds read in stb_truetype.h in stb 1.26 and earlier allows remote attackers to crash applications via crafted fonts. The published proof of concept reaches stbtt__buf_get8 from stbtt_InitFont_internal during CFF parsing and records a one-byte read 26 bytes beyond a 212-byte heap allocation. Public evidence does not explain how the buffer's cursor/size invariant is defeated; exploitation requires a host application to process attacker-supplied font data, and only a crash is demonstrated.
Summary
What happened
Out-of-bounds read in stb_truetype.h in stb 1.26 and earlier allows remote attackers to crash applications via crafted fonts. The published proof of concept reaches stbtt__buf_get8 from stbtt_InitFont_internal during CFF parsing and records a one-byte read 26 bytes beyond a 212-byte heap allocation. Public evidence does not explain how the buffer's cursor/size invariant is defeated; exploitation requires a host application to process attacker-supplied font data, and only a crash is demonstrated.
The record
- CVE
- CVE-2026-5315
- Published
- Apr 1, 2026
- Updated
- Apr 1, 2026
- Vendor
- Sean Barrett
- Product
- stb
- Classifications
- CWE-125, CWE-119, T1204.002
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Apr 1, 2026CVE publishedPublication date reported by the CVE source.
- Apr 1, 2026Record 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=1.0
- Affected versionversion=1.1
- Affected versionversion=1.10
- Affected versionversion=1.11
- Affected versionversion=1.12
- Affected versionversion=1.13
- Affected versionversion=1.14
- Affected versionversion=1.15
- Affected versionversion=1.16
- Affected versionversion=1.17
- Affected versionversion=1.18
- Affected versionversion=1.19
- Affected versionversion=1.2
- Affected versionversion=1.20
- Affected versionversion=1.21
- Affected versionversion=1.22
- Affected versionversion=1.23
- Affected versionversion=1.24
- Affected versionversion=1.25
- Affected versionversion=1.26
- Affected versionversion=1.3
- Affected versionversion=1.4
- Affected versionversion=1.5
- Affected versionversion=1.6
- Affected versionversion=1.7
- Affected versionversion=1.8
- Affected versionversion=1.9
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
- stb_truetype.h buf_get8 OOB Read PoCproof 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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