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CVE-2021-21017

Adobe Acrobat and Reader Heap-based Buffer Overflow

8.8 HIGHActively exploited (CISA KEV)EPSS 86.3%
  1. Published11 Feb 2021
  2. Added to CISA KEV3 Nov 2021
  3. Remediation due17 Nov 2021
Actively exploited (CISA KEV)

Acrobat Acrobat and Reader contain a heap-based buffer overflow vulnerability that could allow an unauthenticated attacker to achieve code execution in the context of the current user.

Added to KEV: 3 Nov 2021Federal remediation due: 17 Nov 2021

Description

Acrobat Reader DC versions versions 2020.013.20074 (and earlier), 2020.001.30018 (and earlier) and 2017.011.30188 (and earlier) are affected by a heap-based buffer overflow 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.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionRequired
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected products

Adobe Acrobat≥ 17.0 ≤ 17.011.30188 · ≥ 20.0 ≤ 20.001.30018
Adobe Acrobat Dc≤ 20.013.20074
Adobe Acrobat Reader≥ 17.0 ≤ 17.011.30188 · ≥ 20.0 ≤ 20.001.300183
Adobe Acrobat Reader Dc≤ 20.013.20074

Remediation

No fixed version is recorded in the NVD data. Check the vendor advisory for the latest guidance.

References

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Frequently asked

Is CVE-2021-21017 being actively exploited?

Yes. CVE-2021-21017 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added 3 Nov 2021.

How severe is CVE-2021-21017?

CVE-2021-21017 has a CVSS 3.1 base score of 8.8, rated high. EPSS estimates a 86.3% probability of exploitation.

Which products are affected by CVE-2021-21017?

Affected products include Adobe Acrobat, Adobe Acrobat Dc, Adobe Acrobat Reader, Adobe Acrobat Reader Dc.

How do I fix CVE-2021-21017?

Apply the vendor's patch or advisory guidance, then verify no affected versions remain across your devices.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2021-21017 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. Because it is on the CISA KEV list, Secuno flags any affected asset as top-priority automatically. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.