CVE-2021-39853
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 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 confidenceA null pointer dereference vulnerability exists in Adobe Acrobat Reader DC that allows an unauthenticated attacker to cause a denial-of-service by convincing a victim to open a specially crafted malicious PDF file. The vulnerability triggers when the application attempts to dereference a null pointer while processing the malformed file, causing the application to crash.
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>= 15.008.20082, <= 21.005.20060>= 15.008.20082, <= 21.005.20058>= 15.008.20082, <= 21.005.20060>= 20.001.30005, <= 20.004.30006>= 20.001.30005, <= 20.004.30006CVSS 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:3.1/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 checksWork through these to decide whether this CVE applies to you.
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Identify installed Adobe productOpen Adobe Acrobat Reader DC or Adobe Acrobat, go to Help > About Adobe Acrobat Reader (or About Adobe Acrobat). Note whether it says 'Reader' or just 'Acrobat' (the Pro version).Affected if The product is Adobe Acrobat Reader DC or Adobe Acrobat (any version within the affected ranges).
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Determine the installed version numberIn the About dialog, locate the exact version number displayed (for example: 21.005.20060 or 20.004.30006). Record the full version string including the four-digit release number.Affected if The version falls within >= 15.008.20082 and <= 21.005.20060 for DC versions, or >= 20.001.30005 and <= 20.004.30006 for 2020 versions.
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Compare version against affected rangesMatch your installed version to the following ranges: For DC (2021): 15.008.20082 through 21.005.20060 are affected. For 2020: 20.001.30005 through 20.004.30006 are affected. For 2017: 15.008.20082 through versions below 2017.011.30199 are affected.Affected if Your installed version is within any of these ranges, indicating the vulnerability is present.
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Verify PDF handling is enabledConfirm that the Adobe application is configured to handle PDF files as a default PDF viewer, or that users routinely open PDF documents using this installation.Affected if The application is used to open PDF files, as the exploitation requires a victim to open a specially crafted malicious PDF.
You are affected if Adobe Acrobat Reader DC or Adobe Acrobat is installed with a version between 15.008.20082 and 21.005.20060 (DC/2021 track) or between 20.001.30005 and 20.004.30006 (2020 track), and the application is used to open PDF documents.
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.
From vendor dataUpdate Adobe Acrobat Reader DC to a version newer than 2021.005.20060, 2020.004.30006, or 2017.011.30199 depending on the release track in use.
- Consultation2.0 h
- Implementation4.0 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-2021-39853 — 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-2021-39853 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
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