Code execution via out-of-bounds FLAC write
Published May 11, 2021 · Updated May 28, 2026
Out-of-bounds write in Microsoft Web Media Extensions before 1.0.40831.0 allows remote attackers to execute code through a crafted FLAC file. The FLAC parser fails to validate user-supplied data before writing past the end of an allocated buffer. Exploitation requires the target to visit a malicious page or open a malicious file, and resulting code runs as the current user at low integrity.
Summary
What happened
Out-of-bounds write in Microsoft Web Media Extensions before 1.0.40831.0 allows remote attackers to execute code through a crafted FLAC file. The FLAC parser fails to validate user-supplied data before writing past the end of an allocated buffer. Exploitation requires the target to visit a malicious page or open a malicious file, and resulting code runs as the current user at low integrity.
The record
- CVE
- CVE-2021-28465
- Published
- May 11, 2021
- Updated
- May 28, 2026
- Vendor
- Microsoft
- Product
- Web Media Extensions
- Classifications
- CWE-787, T1203
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 11, 2021CVE publishedPublication date reported by the CVE source.
- May 28, 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=1.0.0.0 <1.0.40831.0
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.
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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