CVE-2021-39842
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 · uneditedAcrobat Reader DC versions 2021.005.20060 (and earlier), 2020.004.30006 (and earlier) and 2017.011.30199 (and earlier) are affected by a use-after-free vulnerability that could result in 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 · high confidenceA use-after-free vulnerability exists in Adobe Acrobat Reader DC where memory is accessed after being freed, potentially allowing arbitrary code execution. The vulnerability can be triggered when a victim opens a specially crafted malicious PDF file.
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>= 20.001.30005, <= 20.004.30006>= 17.011.30059, <= 17.011.30199>= 20.001.30005, <= 20.004.30006>= 17.011.30059, <= 17.011.30199>= 15.008.20082, <= 21.005.20058>= 15.008.20082, <= 21.005.20060>= 15.008.20082, <= 21.005.20058>= 15.008.20082, <= 21.005.20060CVSS 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:3.0/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 checksWork through these to decide whether this CVE applies to you.
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Identify installed Adobe productCheck for Adobe Acrobat or Adobe Acrobat Reader DC installation. On Windows, look in Program Files or Program Files (x86) for folders named 'Adobe' or check Add/Remove Programs. On macOS, check /Applications for Adobe Acrobat or Adobe Acrobat Reader.Affected if Adobe Acrobat or Adobe Acrobat Reader DC is installed
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Determine product versionRight-click on the Adobe Acrobat/Reader executable (e.g., AcroRd32.exe or AcroTray.exe), select Properties, and check the Details tab for Product Version. Alternatively, open Adobe Reader/Acrobat, go to Help > About Adobe Acrobat/Reader to view the exact version number.Affected if Version falls within any of the affected ranges: 20.001.30005 through 20.004.30006, 17.011.30059 through 17.011.30199, 15.008.20082 through 21.005.20058, or 15.008.20082 through 21.005.20060
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Check if PDF handling is enabledVerify that the Adobe product is configured to open PDF files. Confirm the PDF file association handler is active (check default file type associations in Windows Explorer or macOS Finder).Affected if PDF files can be opened by the Adobe product (this is the default configuration for Acrobat/Reader)
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Verify product edition typeDetermine if the installed product is the Continuous track or the Classic track. Check the version string format: Continuous versions typically have 5-digit build numbers (e.g., 21.005.20058), while Classic track versions have different numbering (e.g., 20.004.30006).Affected if Product matches the affected version ranges for either Continuous or Classic tracks
A user is affected if they have Adobe Acrobat or Acrobat Reader DC installed with a version number matching any of the specified vulnerable ranges and they open PDF files with the application.
Generated from the published advisory. Verify against your own configuration.
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 · scopedUpdate Adobe Acrobat Reader DC to the latest version. Avoid opening untrusted or unexpected PDF files from unverified sources.
Acrobat Reader DC / Acrobat DC: 2021.006.20092 or later (2021 track), 2020.004.30007 or later (2020 track), 2017.011.30200 or later (2017 track)
- 1. Verify the currently installed Adobe Acrobat or Adobe Acrobat Reader DC version by opening the application, selecting Help > About Adobe Acrobat Reader DC (or About Adobe Acrobat).
- 2. Identify which version branch you are on: 2021.x, 2020.x, or 2017.x based on the version number shown.
- 3. For version 2021.005.20060 or earlier: Upgrade to version 2021.006.20092 or later.
- 4. For version 2020.004.30006 or earlier: Upgrade to version 2020.004.30007 or later.
- 5. For version 2017.011.30199 or earlier: Upgrade to version 2017.011.30200 or later.
- 6. Download the latest version from the official Adobe website at https://get.adobe.com/reader/ (for Reader) or https://get.adobe.com/acrobat/ (for Acrobat).
- 7. Run the installer and follow the prompts to complete the upgrade.
- 8. Restart the application after installation completes.
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation1.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-39842 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-39842 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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