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Acrobat Reader Dc CVE-2021-40726

HIGH
Use After Free (CWE-416)
2021-10-07 psirt@adobe.com
7.8
CVSS 3.0 · Vendor: adobe
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Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Memory lifecycle management
MITRE ATT&CK

2 techniques across 2 tactics: Execution, Privilege Escalation

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Impact

CVSS score of 7.8 (HIGH). Attack characteristics: local attack vector, low complexity, no privileges required, user interaction required.

Exploit ScenarioDerived

A local attacker with access to the system could access freed memory to execute arbitrary code or crash the application. No authentication is required to exploit this vulnerability.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
No patch listed yet 5.1% exploitation probability (EPSS)

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AnalysisAI

Acrobat Reader DC versions 2021.005.20060 (and earlier), 2020.004.30006 (and earlier) and 2017.011.30199 (and earlier) are affected by a use-after-free vulnerability when processing AcroForm field. Rated high severity (CVSS 7.8), this vulnerability is no authentication required, low attack complexity. No vendor patch available.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Use smart pointers or garbage-collected languages. Set pointers to NULL after freeing. Enable memory sanitizers.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified as Use After Free (CWE-416), which allows attackers to access freed memory to execute arbitrary code or crash the application. Acrobat Reader DC versions 2021.005.20060 (and earlier), 2020.004.30006 (and earlier) and 2017.011.30199 (and earlier) are affected by a use-after-free vulnerability when processing AcroForm field that could result in arbitrary code execution in the context of the current user. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file. Affected products include: Adobe Acrobat Dc, Adobe Acrobat Reader Dc.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (adobe) PRIMARY 7.8 HIGH
AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Primary rating from Vendor (adobe) · only source for this CVE.

CVSS VectorVendor: adobe

Attack Vector
Local
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

DescriptionCVE.org

Acrobat Reader DC versions 2021.005.20060 (and earlier), 2020.004.30006 (and earlier) and 2017.011.30199 (and earlier) are affected by a use-after-free vulnerability when processing AcroForm field that could result in arbitrary code execution in the context of the current user. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file.

Threat Intelligence Overview

EPSS Score
5.1%
Top 9% exploitable
Data Quality
2 sources
Confidence: Low

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS 5.1%
Patch available No
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Defer
Exploitation· derived
None
System Exposure· derived
Small
Automatable· derived
No
Human Impact· derived
Medium

Priority Score

44
Low Medium High Critical
KEV: 0
EPSS: +5
CVSS: +39
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Use-after-free vulnerabilities occur when a program continues to access memory through a pointer after that memory has been deallocated.

Memory corruption occurs when a program writes data beyond the boundaries of allocated memory regions or accesses memory in unintended ways, violating the integrity of the process's address space.

Remote Code Execution represents the critical moment when an attacker successfully runs arbitrary code on a target system without physical access.

Affected Products (CPE)CVE.org

cpe:2.3:a:adobe:acrobat_dc:*:*:*:*:classic:*:*:*
cpe:2.3:a:adobe:acrobat_reader_dc:*:*:*:*:classic:*:*:*
cpe:2.3:a:adobe:acrobat_dc:*:*:*:*:classic:*:*:*
cpe:2.3:a:adobe:acrobat_reader_dc:*:*:*:*:classic:*:*:*
cpe:2.3:a:adobe:acrobat_dc:*:*:*:*:continuous:*:*:*
cpe:2.3:a:adobe:acrobat_reader_dc:*:*:*:*:continuous:*:*:*
cpe:2.3:a:adobe:acrobat_dc:*:*:*:*:continuous:*:*:*
cpe:2.3:a:adobe:acrobat_reader_dc:*:*:*:*:continuous:*:*:*
CVE-2026-34621 HIGH POC
8.6 Apr 11

Prototype pollution in Adobe Acrobat Reader versions 24.001.30356, 26.001.21367 and earlier enables arbitrary code execu

CVE-2016-4203 CRITICAL POC
9.8 Jul 13

Adobe Reader and Acrobat before 11.0.17, Acrobat and Acrobat Reader DC Classic before 15.006.30198, and Acrobat and Acro

CVE-2015-7622 CRITICAL POC
10.0 Oct 14

Adobe Reader and Acrobat 10.x before 10.1.16 and 11.x before 11.0.13, Acrobat and Acrobat Reader DC Classic before 2015.

CVE-2016-4208 CRITICAL POC
9.8 Jul 13

Adobe Reader and Acrobat before 11.0.17, Acrobat and Acrobat Reader DC Classic before 15.006.30198, and Acrobat and Acro

CVE-2016-4207 CRITICAL POC
9.8 Jul 13

Adobe Reader and Acrobat before 11.0.17, Acrobat and Acrobat Reader DC Classic before 15.006.30198, and Acrobat and Acro

CVE-2016-4206 CRITICAL POC
9.8 Jul 13

Adobe Reader and Acrobat before 11.0.17, Acrobat and Acrobat Reader DC Classic before 15.006.30198, and Acrobat and Acro

CVE-2016-4205 CRITICAL POC
9.8 Jul 13

Adobe Reader and Acrobat before 11.0.17, Acrobat and Acrobat Reader DC Classic before 15.006.30198, and Acrobat and Acro

CVE-2016-4204 CRITICAL POC
9.8 Jul 13

Adobe Reader and Acrobat before 11.0.17, Acrobat and Acrobat Reader DC Classic before 15.006.30198, and Acrobat and Acro

CVE-2016-4201 CRITICAL POC
9.8 Jul 13

Adobe Reader and Acrobat before 11.0.17, Acrobat and Acrobat Reader DC Classic before 15.006.30198, and Acrobat and Acro

CVE-2016-1077 CRITICAL POC
9.8 May 11

Adobe Reader and Acrobat before 11.0.16, Acrobat and Acrobat Reader DC Classic before 15.006.30172, and Acrobat and Acro

CVE-2017-16385 HIGH
8.8 Dec 09

An issue was discovered in Adobe Acrobat and Reader: 2017.012.20098 and earlier versions, 2017.011.30066 and earlier ver

CVE-2017-16396 HIGH
8.8 Dec 09

An issue was discovered in Adobe Acrobat and Reader: 2017.012.20098 and earlier versions, 2017.011.30066 and earlier ver

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