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AcrobatApplication · Adobe

CVE-2021-39845

MEDIUM · 6.1 CVSS v3.1 Published 2021-09-29
Fix available
A fix is available. Upgrade to after 21.005.20060 or later.
See remediation →
64/100
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 stack overflow vulnerability due to insecure handling of a crafted PDF file, potentially resulting in memory corruption in the context of the current user. Exploitation requires user interaction in that a victim must open a crafted PDF file in Acrobat Reader.

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

Stack overflow vulnerability in Adobe Acrobat Reader DC when processing maliciously crafted PDF files, leading to memory corruption in the current user's context. Exploitation requires the victim to open a specially crafted PDF file.

MitigationUpdate Adobe Acrobat Reader DC to the latest version and exercise caution when opening PDF files from untrusted 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:>= 20.001.30005, <= 20.004.30006>= 17.011.30059, <= 17.011.30199
Acrobat ReaderApplication
Affected:>= 20.001.30005, <= 20.004.30006>= 17.011.30059, <= 17.011.30199
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
Low
Availability
High

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:L/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. Identify the installed Adobe product
    Open Adobe Acrobat Reader or Acrobat, then go to Help > About Adobe Acrobat Reader (or Acrobat) to see the exact product name and version number displayed in the dialog window
    Affected if The product is Adobe Acrobat, Adobe Acrobat Reader, Adobe Acrobat DC, or Adobe Acrobat Reader DC
  2. Note the exact version number
    Record the full version number shown in the About dialog (for example: 20.004.30006 or 21.005.20058)
    Affected if Version cannot be determined or is not visible
  3. Compare against affected version ranges
    Check if your version falls within any of these ranges: Acrobat/Acrobat Reader 20.001.30005 to 20.004.30006, 17.011.30059 to 17.011.30199; Acrobat DC/Reader DC 15.008.20082 to 21.005.20058 (Classic) or 15.008.20082 to 21.005.20060 (Continuous)
    Affected if Installed version is greater than or equal to 20.001.30005 and less than or equal to 20.004.30006, OR greater than or equal to 17.011.30059 and less than or equal to 17.011.30199, OR greater than or equal to 15.008.20082 and less than or equal to 21.005.20058 (for some DC variants) or 21.005.20060 (
  4. Determine the product track
    Check whether the installation is the Classic (15.x-20.x) or Continuous (21.x) track by looking at the version number format - Classic versions are in the 15.x-20.x range while Continuous versions are 21.x
    Affected if Using the Classic track version 15.x-20.x or Continuous track version 21.x within the affected ranges

A user is affected if Adobe Acrobat or Acrobat Reader DC/Classic is installed with a version number matching any of the documented affected ranges and the user opens a specially crafted malicious PDF file.

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 and exercise caution when opening PDF files from untrusted sources.

Recommended fix High confidence

Acrobat/Acrobat Reader DC 2021.006.20080+, 2020.005.30018+, or 2017.012.30233+ (depending on your product track)

  1. Identify the installed Adobe Acrobat or Acrobat Reader version by opening the application and navigating to Help > About Adobe Acrobat Reader (or About Adobe Acrobat)
  2. For version 2021.x (2021.005.20060 and earlier): Upgrade to version 2021.006.20080 or later
  3. For version 2020.x (2020.004.30006 and earlier): Upgrade to version 2020.005.30018 or later
  4. For version 2017.x (2017.011.30199 and earlier): Upgrade to version 2017.012.30233 or later
  5. Download the latest version from helpx.adobe.com or use the built-in Help > Check for Updates functionality
  6. Restart the application after installation
  7. Verify the installed version reflects the patched release
Caveat Standard minor version upgrade; existing PDF workflows and settings should be preserved

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

Fix this in Acrobat 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-2021-39845 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