CVE-2021-28550
Exploited in the Wild
✓ Confirmed 0-Day
★ Google Project Zero
Triaged: March 3, 2026
4 articles
EPSS Score
Source: FIRST.org · 2026-05-24
30.72%
probability
This CVE has a 30.72% probability
of being exploited in the next 30 days.
0%
Top 96.8th percentile of all CVEs
100%
CVSS score unavailable
Neither CIRCL nor NVD returned a CVSS score for this CVE.
View on VulnerabilityLookup ↗
Description
Project ZeroUse-after-free
Attack Intelligence
CWE-118
· Incorrect Access of Indexable Resource ('Range Error')
CWE-119
· Buffer Overflow
CWE-416
· Use After Free
CWE-664
· Improper Control of a Resource Through its Lifetime
CWE-666
· Operation on Resource in Wrong Phase of Lifetime
CWE-672
· Operation on a Resource after Expiration or Release
CWE-825
· Expired Pointer Dereference
Google Project Zero
Patched
May 11, 2021
Reported by
???
Root Cause Analysis
???
Microsoft & Adobe Patch Tuesday (May 2021) – Qualys covers 85 Vulnerabilities, 26 Critical
Qualys
May 11, 2021
Adobe fixes Reader zero-day vulnerability exploited in the wild
BleepingComputer
May 11, 2021
Security Advisory 2021-024
CERT-EU
May 12, 2021
Qualys Response to CISA Alert: Binding Operational Directive 22-01
Qualys
Nov 09, 2021
Signal Intelligence
Confidence
92%
EPSS
30.72%
Mentions
4
Last Seen
Nov 09, 2021
CNA Information
Analyst Note
CVE-2021-28550 is confirmed as a critical use-after-free vulnerability in Adobe Acrobat Reader with CVSS 9.6, affecting multiple widely-deployed versions and requiring only user interaction for exploitation. The classification is strongly supported by official Adobe advisories, coverage in CERT-EU security guidance, and inclusion in Google Project Zero tracking, demonstrating widespread awareness and validation within the security community.
Triage Info
Decided atMar 03, 2026