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CVE

CVE-2021-28550

Adobe Acrobat and Reader Use-After-Free Vulnerability

Acrobat Reader DC versions 2021.001.20150 (and earlier), 2020.001.30020 (and earlier) and 2017.011.30194 (and earlier) are affected by a Use After Free vulnerability. An unauthenticated attacker could leverage this vulnerability to achieve arbitrary code execution in the context of the current user. Exploitation of this issue requires user interaction in that a victim must open a malicious file.

HIGH · CVSS 8.8 ⚠ CISA KEV EPSS 0.30724
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  • Listed on CISA KEV (known exploited in the wild)
  • SSVC exploitation status: active
  • EPSS ≥ 0.10 - elevated exploitation probability
  • EPSS percentile: top 3% of all CVEs by exploitation likelihood
  • CVSS base score ≥ 7.0
Sigma rules15 YARA rules0
⬢

Required Remediation

Apply updates per vendor instructions.

◆

Threat Actors Linked

1
actorDSIRF (Knotweed)
⬡

Weakness Classification

CWE-416Use After Free
▤

Affected Products & Versions

8
adobe acrobat dc>= 15.008.20082 and <= 21.001.20150
adobe acrobat reader dc>= 15.008.20082 and <= 21.001.20150
adobe acrobat>= 17.011.30059 and <= 17.011.30194
adobe acrobat>= 20.001.30005 and <= 20.001.30020
adobe acrobat reader>= 17.011.30059 and <= 17.011.30194
adobe acrobat reader>= 20.001.30005 and <= 20.001.30020
adobe acrobat dc>= 15.008.20082 and <= 21.001.20149
adobe acrobat reader dc>= 15.008.20082 and <= 21.001.20149
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Sigma Hunt Rules

15
Exact rules name this CVE ID. Product rules name an affected product in their title. Related rules cover techniques used by actors who exploited this CVE. Showing the most relevant matches; the complete related set is on the full drill-down.
productcriticalHackTool - Windows Credential Editor (WCE) Execution
productcriticalWindows Credential Editor Registry
producthighOpenCanary - MSSQL Login Attempt Via Windows Authentication
producthighWindows LAPS Credential Dump From Entra ID
producthighTamper Windows Defender - PSClassic
producthighTamper Windows Defender Remove-MpPreference - ScriptBlockLogging
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Scoring & Timeline

8.8
HIGH · CVSS v3.1 · psirt@adobe.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD02 Sep 2021 · 05:15 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
SSVC triage · cisa-vulnrichment
Exploitation
active
Automatable
no
Technical impact
total
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
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Vendor Advisories

2
cisaKEV-CVE-2021-28550
adobe-psirtAPSB21-29
🔗

References & Sources

1
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-28550Third Party AdvisoryUS Government Resource
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