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Acrobat DcApplication · Adobe

CVE-2021-28551

HIGH · 7.8 CVSS v3.1 Published 2021-08-24
Fix available
A fix is available. Upgrade to after 21.001.20150 or later.
See remediation →
81/100
Remediation priority · High
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 versions 2021.001.20155 (and earlier), 2020.001.30025 (and earlier) and 2017.011.30196 (and earlier) are affected by an Out-of-bounds read vulnerability. An unauthenticated attacker could leverage this vulnerability to achieve arbitrary code execution 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 · moderate confidence

This is an out-of-bounds read vulnerability in Adobe Acrobat Reader DC that allows an unauthenticated attacker to achieve arbitrary code execution in the context of the current user. Exploitation requires the victim to open a malicious PDF file, making this a client-side attack vector.

MitigationUpdate Adobe Acrobat Reader DC to a patched version beyond 2021.001.20155, 2020.001.30025, or 2017.011.30196. Additionally, train users to avoid opening untrusted or unexpected PDF attachments.

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, <= 21.001.20150>= 15.008.20082, <= 21.001.20149
Acrobat Reader DcApplication
Affected:>= 15.008.20082, <= 21.001.20150>= 15.008.20082, <= 21.001.20149
AcrobatApplication
Affected:>= 17.011.30180, <= 17.011.30194>= 20.001.30005, <= 20.001.30020
Acrobat ReaderApplication
Affected:>= 17.011.30180, <= 17.011.30194>= 20.001.30005, <= 20.001.30020

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
High

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/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 installed Adobe product
    Open Adobe Acrobat Reader or Acrobat, then go to Help > About Adobe Acrobat Reader (or About Adobe Acrobat) to view the exact version number. Alternatively, check Add/Remove Programs (Windows) or Applications folder (Mac).
    Affected if The installed product is Adobe Acrobat DC, Adobe Acrobat Reader DC, Adobe Acrobat, or Adobe Acrobat Reader
  2. Confirm version for Acrobat Reader DC or Acrobat DC
    Look for the version in the format 21.x.x.xxxxx or 15.x.x.xxxxx in the About dialog. Record the full version number including the last five digits.
    Affected if The version is between 15.008.20082 and 21.001.20150 inclusive, or between 15.008.20082 and 21.001.20149 inclusive (check both ranges)
  3. Confirm version for Acrobat or Acrobat Reader (classic)
    Look for the version in the format 17.x.xxxxxx or 20.x.xxxxx in the About dialog. Record the full version number.
    Affected if The version is between 17.011.30180 and 17.011.30194 inclusive, or between 20.001.30005 and 20.001.30020 inclusive (check both ranges)
  4. Verify PDF handling exposure
    This vulnerability is triggered when a user opens a malicious PDF file. Check whether the system routinely opens PDF files from untrusted sources or email attachments.
    Affected if Users in the environment open PDF files from external or untrusted sources without verification

You are affected if Adobe Acrobat or Acrobat Reader is installed with a version matching the affected ranges: 15.008.20082 to 21.001.20150, 17.011.30180 to 17.011.30194, or 20.001.30005 to 20.001.30020.

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 21.001.20150
Interim mitigation

Update Adobe Acrobat Reader DC to a patched version beyond 2021.001.20155, 2020.001.30025, or 2017.011.30196. Additionally, train users to avoid opening untrusted or unexpected PDF attachments.

Recommended fix High confidence

Acrobat/Reader 2021.x → 2021.001.20156+ | 2020.x → 2020.001.30026+ | 2017.x → 2017.011.30197+

  1. 1. Identify the current Adobe Acrobat/Reader version by opening the application and navigating to Help > About Adobe Acrobat Reader (or About Adobe Acrobat)
  2. 2. For 2021.x track users: Upgrade to version 2021.001.20156 or later
  3. 3. For 2020.x track users: Upgrade to version 2020.001.30026 or later
  4. 4. For 2017.x track users: Upgrade to version 2017.011.30197 or later
  5. 5. Download the appropriate updated version from the official Adobe website or use the application's built-in update feature (Help > Check for Updates)
  6. 6. Install the update and restart the application
  7. 7. Verify the installed version matches or exceeds the fixed release for your track
Caveat Standard Adobe update; may require acceptance of new license terms; ensure compatibility with other PDF tools in your 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
  • 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-2021-28551 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