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Acrobat DcApplication · Adobe

CVE-2021-35985

MEDIUM · 5.5 CVSS v3.1 Published 2021-08-20
Fix available
A fix is available. Upgrade to after 21.005.20054 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 2021.005.20054 (and earlier), 2020.004.30005 (and earlier) and 2017.011.30197 (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

A null pointer dereference vulnerability exists in Adobe Acrobat Reader DC versions 2021.005.20054 and earlier, 2020.004.30005 and earlier, and 2017.011.30197 and earlier. An unauthenticated attacker can craft a malicious PDF file that, when opened by a victim, triggers a null pointer dereference causing the application to crash, resulting in denial-of-service in the context of the current user.

MitigationUpdate Adobe Acrobat Reader DC to the latest patched version. Additionally, enforce user awareness training to avoid opening untrusted PDF attachments from unknown sources, and consider implementing application whitelisting or sandboxing as defense-in-depth measures.

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
Acrobat DcApplication
Affected:>= 15.008.20082, <= 21.005.20054>= 17.011.30059, <= 17.011.30197>= 20.001.30005, <= 20.004.30005
Acrobat Reader DcApplication
Affected:>= 15.008.20082, <= 21.005.20054>= 17.011.30059, <= 17.011.30197>= 20.001.30005, <= 20.004.30005

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. Check if Adobe Acrobat Reader DC or Adobe Acrobat DC is installed
    Look for the application in the Windows Start Menu, installed programs list, or check for the executable (AcroRd32.exe for Reader or Acrobat.exe for full Acrobat) in the Program Files directory
    Affected if Adobe Acrobat Reader DC or Adobe Acrobat DC is present on the system
  2. Determine the installed version number
    Open the application, then go to Help > About Adobe Acrobat Reader DC (or About Adobe Acrobat DC). Alternatively, check the Windows Registry at HKEY_LOCAL_MACHINE\SOFTWARE\Adobe\Acrobat DC\{VersionNumber} or HKEY_LOCAL_MACHINE\SOFTWARE\Adobe\Acrobat Reader DC\{VersionNumber}
    Affected if The installed version cannot be determined or the application is not found in the registry
  3. Compare the installed version against the affected ranges
    Compare the full version number (for example, 21.001.20235) to these vulnerable ranges: 15.008.20082 through 21.005.20054, 17.011.30059 through 17.011.30197, 20.001.30005 through 20.004.30005
    Affected if The installed version falls within any of these ranges: 15.008.20082 to 21.005.20054, 17.011.30059 to 17.011.30197, or 20.001.30005 to 20.004.30005

If Adobe Acrobat Reader DC or Adobe Acrobat DC is installed and its version falls within any of the listed affected ranges, the environment is vulnerable to CVE-2021-35985.

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 21.005.20054
Interim mitigation

Update Adobe Acrobat Reader DC to the latest patched version. Additionally, enforce user awareness training to avoid opening untrusted PDF attachments from unknown sources, and consider implementing application whitelisting or sandboxing as defense-in-depth measures.

Recommended fix High confidence

Acrobat Reader DC/Acrobat DC 2021.006 or later, 2021.001 or later for 2020 track, or 2017.012 or later (though 2017 is EOL - recommend migrating to supported 2020/2021 versions)

  1. 1. Open Adobe Acrobat Reader DC or Adobe Acrobat DC
  2. 2. Navigate to Help > Check for Updates (or Help > About Adobe Acrobat Reader DC)
  3. 3. Allow the application to check for available updates
  4. 4. If updates are available, download and install the latest version
  5. 5. Alternatively, download the latest version directly from the official Adobe website: https://get.adobe.com/reader/ (for Reader) or https://get.adobe.com/acrobat/ (for Pro)
  6. 6. Restart the application after installation
  7. 7. Verify the installed version by checking Help > About to confirm you are on a fixed release
Caveat Upgrading across major version tracks (e.g., 2017 to 2021) may require new license or subscription; ensure compatibility with existing workflows and plugins

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

Fix this in Acrobat Dc Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
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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-2021-35985 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