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.
- Vendor
- Adobe
- Product
- Acrobat and Reader
- CVSS
- 8.8
- EPSS (exploit probability)
- 86.3%
- Status
- kev
- CISA patch-by (BOD 22-01)
- Added to KEV
Is CVE-2021-21017 being exploited?
Yes. CISA added CVE-2021-21017 to its Known Exploited Vulnerabilities catalog on . CISA only lists a CVE when it has reliable evidence of exploitation in the wild.
FIRST's EPSS model puts the probability of exploitation activity in the next 30 days at 86.3% (scored October 14, 2026).
- CISA KEV[ LISTED ]
- ENISA EUVD (exploited)[ — ]
- CIRCL KEV[ — ]
Catalog snapshot 2026-10-19. Full cross-catalog view: /kev-comparison
What to do
CISA required actionApply updates per vendor instructions.
US federal civilian agencies must remediate by (14 days after listing) under BOD 22-01. Everyone else: that deadline is a sensible upper bound, not a target. Vendor guidance and the NVD record are linked under Source above.
Other Adobe Acrobat and Reader CVEs we track
| CVE / Vulnerability | Severity | CVSS | EPSS | Added to KEV |
|---|---|---|---|---|
| CVE-2009-3459 Adobe Acrobat and Reader Heap-Based Buffer Overflow Vulnerability | [ HIGH ] | 8.8 | 86.6% | |
| CVE-2026-34621 Adobe Acrobat and Reader Prototype Pollution Vulnerability | [ HIGH ] | 8.6 | 2.2% | |
| CVE-2023-21608 Adobe Acrobat and Reader Use-After-Free Vulnerability | [ HIGH ] | 7.8 | 59.4% | |
| CVE-2023-26369 Adobe Acrobat and Reader Out-of-Bounds Write Vulnerability | [ HIGH ] | 7.8 | 6.7% | |
| CVE-2018-4990 Adobe Acrobat and Reader Double Free Vulnerability | [ HIGH ] | 8.8 | 36.2% | |
| CVE-2011-2462 Adobe Reader and Acrobat Universal 3D Memory Corruption Vulnerability | [ CRITICAL ] | 9.8 | 88.9% | |
| CVE-2010-2883 Adobe Acrobat and Reader Stack-Based Buffer Overflow Vulnerability | [ HIGH ] | 7.3 | 81.4% | |
| CVE-2009-4324 Adobe Acrobat and Reader Use-After-Free Vulnerability | [ HIGH ] | 7.8 | 81.9% |