Code execution via mixed-encoding URL concatenation
Published Sep 29, 2021 · Updated Sep 17, 2024
Heap-based buffer overflow in Adobe Acrobat Reader DC allows remote attackers to execute code after a victim opens a crafted PDF. In IA32.api URL construction, the concatenation routine treats an ANSI relative URL as Unicode and copies each source byte twice past the allocated heap buffer. The victim must open a malicious PDF with embedded JavaScript, and successful exploitation runs code with the victim's privileges.
Summary
What happened
Heap-based buffer overflow in Adobe Acrobat Reader DC allows remote attackers to execute code after a victim opens a crafted PDF. In IA32.api URL construction, the concatenation routine treats an ANSI relative URL as Unicode and copies each source byte twice past the allocated heap buffer. The victim must open a malicious PDF with embedded JavaScript, and successful exploitation runs code with the victim's privileges.
The record
- CVE
- CVE-2021-39863
- Published
- Sep 29, 2021
- Updated
- Sep 17, 2024
- Vendor
- Adobe
- Product
- Adobe Acrobat Reader
- Classifications
- CWE-122, T1203, T1204.002
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 29, 2021CVE publishedPublication date reported by the CVE source.
- Sep 17, 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=unspecified <=17.0-Classic 2021 July
- Affected versionversion=unspecified <=20.0-Classic 2021 July
- Affected versionversion=unspecified <=DC 2021 July
- Affected versionversion=unspecified <=None
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
- Exodus Intelligence CVE-2021-39863 exploit walkthroughfunctional · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
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