CVE-2021-21017
Published: November 3, 2021
Official Description
Acrobat Acrobat and Reader contain a heap-based buffer overflow vulnerability that could allow an unauthenticated attacker to achieve code execution in the context of the current user.
CISA KEV Advisory
Adobe Acrobat and Reader Heap-based Buffer Overflow Vulnerability
Acrobat Acrobat and Reader contain a heap-based buffer overflow vulnerability that could allow an unauthenticated attacker to achieve code execution in the context of the current user.
Apply updates per vendor instructions.
Risk Analysis
This vulnerability in Adobe Acrobat and Reader is a heap-based buffer overflow that could allow an unauthenticated attacker to execute code. Its high EPSS score of 0.90641 indicates a very high likelihood of exploitation, making it an urgent concern. The fact that it is in CISA's KEV catalog confirms it has been actively exploited.
This vulnerability is being actively exploited in the wild and is listed in CISA's KEV catalog, indicating confirmed real-world exploitation. It is remotely exploitable.
Update Adobe Acrobat and Reader to the latest versions to mitigate this heap-based buffer overflow vulnerability. Ensure all users are running patched software to prevent code execution.
Technical Analysis
CVE-2021-21017 requires local access, meaning attackers must already have a foothold on the target system.
Exploitation requires some privileges, which limits the exposure to scenarios where an attacker has already gained initial access.
CISA has added CVE-2021-21017 to the Known Exploited Vulnerabilities (KEV) catalog, confirming active exploitation in the wild. U.S. federal agencies are required to patch this within the mandated timeframe, and all organizations should treat remediation as urgent.
Exploit & PoC Resources
All References (1)
Quick Facts
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2021-21017 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts
- !CISA KEV: Federal agencies must patch per BOD 22-01 timeline
- !Active exploitation confirmed — treat as P1