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Acrobat DcApplication · Adobe

CVE-2021-39854

MEDIUM · 5.5 CVSS v3.0 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

A null pointer dereference vulnerability in Adobe Acrobat Reader DC allows an unauthenticated attacker to cause a denial-of-service condition via a maliciously crafted PDF file that must be opened by the victim.

MitigationUpdate Adobe Acrobat Reader DC to the latest patched version (2021.006.20060 or later for the 2021 track, 2021.001.21129 or later for the 2020 track, and 2017.011.30210 or later for the 2017 track).

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, <= 21.005.20060>= 15.008.20082, <= 21.005.20058
Acrobat Reader DcApplication
Affected:>= 15.008.20082, <= 21.005.20060
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

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:3.0/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. Locate Adobe Acrobat or Reader installation
    On Windows, check the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Adobe\Acrobat or HKEY_LOCAL_MACHINE\SOFTWARE\Adobe\Acrobat Reader, under the version-specific subkey (e.g., DC\Install). On macOS, inspect /Applications/Adobe Acrobat Reader DC.app or /Applications/Adobe Acrobat DC.app and open the application, then check Help > About Adobe Acrobat Reader (or About Adobe Acrobat).
    Affected if The application is installed and the PDF handling functionality is present.
  2. Determine the exact installed version number
    Read the Version or VersionNumber value from the registry location above, or note the version displayed in the About dialog. Record the full version string (for example, 21.005.20060 or 20.004.30006).
    Affected if A version number is returned from the installation.
  3. Compare the installed version against affected ranges
    Check if the installed version falls within any of these ranges: 15.008.20082 through 21.005.20060 (Acrobat/Reader DC), 17.011.30059 through 17.011.30199 (Acrobat/Reader 2017), or 20.001.30005 through 20.004.30006 (Acrobat/Reader 2020). Versions within these bounds are affected.
    Affected if The installed version is greater than or equal to the lower bound and less than or equal to the upper bound of any affected range.
  4. Confirm the product type is vulnerable
    Verify whether the installed product is Adobe Acrobat (full) or Adobe Acrobat Reader. Both product lines are affected according to the CVE. Reader is vulnerable when PDF files can be opened and processed by the application.
    Affected if The product is Adobe Acrobat DC, Adobe Acrobat Reader DC, Adobe Acrobat 2017, Adobe Acrobat Reader 2017, Adobe Acrobat 2020, or Adobe Acrobat Reader 2020.

The environment is affected if Adobe Acrobat or Acrobat Reader is installed with a version number within any of the specified vulnerable ranges (15.008.20082-21.005.20060, 17.011.30059-17.011.30199, or 20.001.30005-20.004.30006).

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 patched version (2021.006.20060 or later for the 2021 track, 2021.001.21129 or later for the 2020 track, and 2017.011.30210 or later for the 2017 track).

Recommended fix Moderate confidence

Latest Adobe Acrobat DC / Acrobat Reader DC release (2021.006 or later for Continuous track; 2021.005.20062 or later for Classic track; 2020.004.30007 or later for 2020 track; 2017.011.30200 or later for 2017 track)

  1. Open Adobe Acrobat Reader or Adobe Acrobat
  2. Go to Help > Check for Updates (or use the Help menu)
  3. Allow the application to check for available updates
  4. Download and install the latest version available from the official Adobe update channel
  5. Alternatively, download the latest version manually from the official Adobe website (get.adobe.com/reader for Reader, or get.adobe.com/acrobat for Acrobat)
  6. Restart the application after the update completes
  7. Verify the installed version is beyond the affected versions (2021.005.20060, 2020.004.30006, or 2017.011.30199)
Caveat Standard minor version upgrade - no expected breaking changes for end users; enterprise deployments should test in staging environment

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

Fix this in Acrobat Dc Scoped from the published advisory
  • Consultation1.0 h
  • Implementation1.0 h
  • Testing1.0 h
  • Review / QA1.0 h
4.0 hours of engineering $750
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Scan for this in your stack

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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-2021-39854 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