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AcrobatApplication · Adobe

CVE-2021-39852

MEDIUM · 5.5 CVSS v3.1 Published 2021-09-29
Fix available
A fix is available. Upgrade to after 21.005.20060 or later.
See remediation →
58/100
Remediation priority · Elevated
No privileges

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Acrobat Reader DC versions 2021.005.20060 (and earlier), 2020.004.30006 (and earlier) and 2017.011.30199 (and earlier) are affected by a Null pointer dereference vulnerability. An unauthenticated attacker could leverage this vulnerability to achieve an application denial-of-service in the context of the current user. Exploitation of this issue requires user interaction in that a victim must open a malicious file.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Adobe Acrobat Reader DC contains a null pointer dereference vulnerability in versions 2021.005.20060 and earlier, 2020.004.30006 and earlier, and 2017.011.30199 and earlier. An unauthenticated attacker can cause the application to crash by tricking a user into opening a malicious file, resulting in denial-of-service in the context of the current user.

MitigationUpdate Adobe Acrobat Reader DC to the latest version to patch the null pointer dereference vulnerability. Users should avoid opening untrusted PDF files from unknown sources.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
AcrobatApplication
Affected:>= 17.011.30059, <= 17.011.30199>= 20.001.30005, <= 20.004.30006
Acrobat ReaderApplication
Affected:>= 17.011.30059, <= 17.011.30199>= 20.001.30005, <= 20.004.30006
Acrobat DcApplication
Affected:>= 15.008.20082, <= 21.005.20058>= 15.008.20082, <= 21.005.20060
Acrobat Reader DcApplication
Affected:>= 15.008.20082, <= 21.005.20058>= 15.008.20082, <= 21.005.20060

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
None
User interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Verify Adobe Acrobat or Reader DC is installed
    Check the Windows Registry under HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\{AC76BA86-7AD7-1033-7B44-AA1000000001} for Reader or the corresponding Acrobat key, or look in C:\Program Files\Adobe for Acrobat or Adobe Acrobat Reader folders
    Affected if The product is not found in the expected installation locations or registry keys are missing
  2. Retrieve the installed version number
    Open Windows Command Prompt and run: reg query "HKLM\SOFTWARE\Adobe\Acrobat Distiller\DC\InstallPath" or check the version in the application via Help > About Adobe Acrobat Reader DC
    Affected if The version cannot be determined or the application is not found
  3. Compare version against affected ranges
    Compare your installed version (e.g., 21.005.20060, 20.004.30006, 17.011.30199) against the vulnerable ranges: 17.011.30059-17.011.30199, 20.001.30005-20.004.30006, 15.008.20082-21.005.20058 (DC variants), or 15.008.20082-21.005.20060 (DC variants)
    Affected if The installed version falls within any of these ranges, meaning it is 2021.005.20060 and earlier, 2020.004.30006 and earlier, or 2017.011.30199 and earlier for classic versions, or between 15.008.20082 and 21.005.20058/21.005.20060 for DC versions

The user is affected if Adobe Acrobat or Acrobat Reader DC is installed with a version number within the vulnerable ranges specified in the CVE.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to a release after 21.005.20060
Interim mitigation

Update Adobe Acrobat Reader DC to the latest version to patch the null pointer dereference vulnerability. Users should avoid opening untrusted PDF files from unknown sources.

Recommended fix High confidence

Acrobat/Reader 2017 to 2017.012.20001+; Acrobat/Reader 2020 to 2020.005.30012+; Acrobat/Reader 2021 to 2021.006.20059+

  1. 1. Identify the currently installed Adobe Acrobat or Reader version by opening the application and navigating to Help > About Adobe Acrobat/Reader
  2. 2. Determine which product line and version you have (Acrobat/Acrobat Reader, and the year-based version: 2017, 2020, or 2021)
  3. 3. For Acrobat/Reader 2017 (versions <= 2017.011.30199): Upgrade to version 2017.012.20001 or later
  4. 4. For Acrobat/Reader 2020 (versions <= 2020.004.30006): Upgrade to version 2020.005.30012 or later
  5. 5. For Acrobat/Reader 2021 (versions <= 2021.005.20060): Upgrade to version 2021.006.20059 or later
  6. 6. Download the updated version from the official Adobe website (get.adobe.com/reader for Reader, or adobe.com/downloads for Acrobat)
  7. 7. Close all Adobe applications before running the installer
  8. 8. Run the installer and follow the prompts to complete the update
Caveat Adobe updates typically have minimal breaking changes; however, some legacy features or plugins may not be supported in newer major versions

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Acrobat Scoped from the published advisory
  • Consultation1.0 h
  • Implementation3.0 h
  • Testing1.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,070
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-39852 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data