Arbitrary code execution via stale event.target reference
Published Aug 5, 2021 · Updated Aug 3, 2024
Use-after-free in Foxit PDF Reader 11.0.0.49893 and earlier allows remote attackers to execute arbitrary code via a crafted PDF. During an OnFocus handler, Object.assign retains event.target after event cleanup frees parts of the Field object, and later access reuses that memory. Exploitation requires opening the PDF or visiting a malicious site with the browser plug-in enabled and runs code in the reader process.
Summary
What happened
Use-after-free in Foxit PDF Reader 11.0.0.49893 and earlier allows remote attackers to execute arbitrary code via a crafted PDF. During an OnFocus handler, Object.assign retains event.target after event cleanup frees parts of the Field object, and later access reuses that memory. Exploitation requires opening the PDF or visiting a malicious site with the browser plug-in enabled and runs code in the reader process.
The record
- CVE
- CVE-2021-21893
- Published
- Aug 5, 2021
- Updated
- Aug 3, 2024
- Vendor
- Foxit Software
- Product
- Foxit PDF Reader
- Classifications
- CWE-416, T1204.002, T1203
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 5, 2021CVE publishedPublication date reported by the CVE source.
- Aug 3, 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=Foxit Reader 11.0.0.49893
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
- Field OnFocus event use-after-free proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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