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Acrobat DcApplication · Adobe

CVE-2021-28637

HIGH · 7.1 CVSS v3.1 Published 2021-08-20
Fix available
A fix is available. Upgrade to after 21.005.20054 or later.
See remediation →
74/100
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 an out-of-bounds read vulnerability. An unauthenticated attacker could leverage this vulnerability achieve arbitrary read / write system information 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

This is an out-of-bounds read vulnerability in Adobe Acrobat Reader DC affecting multiple version branches (2017, 2020, and 2021). An unauthenticated attacker can achieve arbitrary read/write of system information by tricking a user into opening a malicious PDF file, executing code in the context of the current user.

MitigationUpdate Adobe Acrobat Reader DC to the latest patched version. Ensure users do not open 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
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
High
Integrity
High
Availability
None

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

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 installed Adobe Acrobat Reader DC version
    Open Adobe Acrobat Reader DC, go to Help > About Adobe Acrobat Reader, or check the version in Add/Remove Programs. Alternatively, right-click the executable (AcroRd32.exe or AcroRd64.exe) in the installation folder and view Properties > Details to see the Product Version.
    Affected if The installed version falls within these ranges: 15.008.20082 to 21.005.20054, OR 17.011.30059 to 17.011.30197, OR 20.001.30005 to 20.004.30005
  2. Confirm the product is Adobe Acrobat Reader DC (not other PDF viewers)
    Verify the product name in Add/Remove Programs is 'Adobe Acrobat Reader DC' or check the executable name in the installation directory (typically C:\Program Files\Adobe\Acrobat DC\AcroRd32.exe or similar).
    Affected if The installed product is Adobe Acrobat Reader DC or Adobe Acrobat DC within the affected version ranges
  3. Verify the PDF file handling is enabled
    Confirm that the PDF file association is set to open PDFs with Adobe Acrobat Reader DC (check Default Apps > PDF in Windows Settings, or right-click any PDF file > Open with > Choose another app).
    Affected if Adobe Acrobat Reader DC is set as the default PDF handler, allowing malicious PDF files to be automatically opened
  4. Check for recent PDF files from untrusted sources
    Review recently downloaded or opened PDF files, particularly from email attachments or untrusted websites. Check browser download folders and email attachments for PDF files.
    Affected if Users have opened or are likely to open PDF files from untrusted or unknown sources

You are affected if Adobe Acrobat Reader DC or Adobe Acrobat DC is installed with a version number matching the affected ranges 15.008.20082-21.005.20054, 17.011.30059-17.011.30197, or 20.001.30005-20.004.30005.

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. Ensure users do not open untrusted PDF files from unknown sources.

Recommended fix Moderate confidence

Adobe Acrobat Reader DC / Acrobat DC version 2021.006.20060 or later (for 2021 track); version 2020.005.30060 or later (for 2020 track); version 2021.001.20100 or later (for 2017 track)

  1. 1. Close all Adobe Acrobat or Acrobat Reader instances that are currently running
  2. 2. Navigate to the official Adobe download page at https://get.adobe.com/reader/ or use your organization's software distribution method
  3. 3. Download the latest version of Adobe Acrobat Reader DC (or Adobe Acrobat DC for your subscription tier)
  4. 4. Run the installer and follow the prompts to complete the installation
  5. 5. After installation, verify the version by opening Adobe Acrobat/Reader and navigating to Help > About Adobe Acrobat Reader DC
  6. 6. Ensure the installed version is newer than the last vulnerable version for your release track (2021.x track: > 21.005.20054, 2020.x track: > 20.004.30005, 2017.x track: > 17.011.30197)
Caveat Standard upgrade considerations apply: ensure compatibility with any existing PDF plugins or workflows; enterprise deployments may require testing in staging environment first

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
  • Implementation2.0 h
  • Testing1.0 h
  • Review / QA1.0 h
5.0 hours of engineering $890
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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-2021-28637 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