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ExploitedIn CISA KEV

CVE-2021-21017

Exploitation confirmed. First attested on 2021-11-03 by CISA-ADP, CISA KEV, GCVE · kevintel.

  • Published2021-02-11
  • WeaknessCWE-122 · CWE-787

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2021-02-1120:15CVE publishedNVD
  2. 2021-11-03Added to the CISA KEV catalogCISA KEV
  3. 2021-11-03Listed as exploited by GCVEGCVE
  4. 2021-11-03Exploitation first reportedCISA KEV
  5. 2025-02-0421:28SSVC exploitation set to activeCISA-ADP

Observed activity

isMalicious corpus · updated 2026-11-03 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-21017?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-21017?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD
Adobe acrobatversion to verify
BranchAffectedFixed in
17.x≥ 17.0, ≤ 17.011.30188no fix published
20.x≥ 20.0, ≤ 20.001.30018no fix published
Adobe acrobat readerversion to verify
BranchAffectedFixed in
17.x≥ 17.0, ≤ 17.011.30188no fix published
20.x≥ 20.0, ≤ 20.001.300183no fix published
Adobe acrobat dcversion to verify
BranchAffectedFixed in
20.13≤ 20.013.20074no fix published

1 more product in the sources.

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Products declared by the CNA1 product

As adobe, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

  • Adobe Acrobat Reader
    Affected
    • ≤ 2020.013.20074no fix statedcustom
    • ≤ 2020.001.30018no fix statedcustom
    • ≤ 2017.011.30188no fix statedcustom
    • ≤ Noneno fix statedcustom

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2021-02-11

Fix

  1. CISA’s required action: Apply updates per vendor instructions.due 2021-11-17

Advisories and patches

Detection

read 2026-11-03 22:42 UTC
Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
2 repositories, unverifiedZeusBox/CVE-2021-21017tzwlhack/CVE-2021-21017
PoC-in-GitHub
Metasploit modules
none listed
Metasploit Framework

CISA Known Exploited Vulnerability

Date Added
2021-11-03
Patch Due Date
2021-11-17
Ransomware Use
Unknown
Required Action
Apply updates per vendor instructions.

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Published
2021-02-11
Last Modified
2026-06-17
NVD status
Analyzed
GitHub Advisory
GHSA-r8q2-5jr4-57f7

Frequently asked questions

What is CVE-2021-21017?

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.

Is CVE-2021-21017 actively exploited?

Yes. CVE-2021-21017 is on the CISA Known Exploited Vulnerabilities (KEV) catalog, meaning it has been confirmed as actively exploited in the wild. CISA requires federal agencies to patch by 2021-11-17.

What is the CVSS score for CVE-2021-21017?

CVE-2021-21017 has a CVSS v3 base score of 8.8 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

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Sources for this record