No exploitation reported

CVE-2021-39843

No exploitation reported by the sources we read.

Published2021-09-29
WeaknessCWE-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 2021.005.20060 (and earlier), 2020.004.30006 (and earlier) and 2017.011.30199 (and earlier) are affected by an out-of-bounds write 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.

Timeline

dates in UTC

2021-09-2916:15CVE publishedNVD
2026-10-2319:23EPSS crossed 10 %FIRST EPSS

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 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-2021-39843?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-39843?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

Branch	Affected	Fixed in	Source
20.x	≥ 20.001.30005, ≤ 20.004.30006	no fix published	NVD
17.11	≥ 17.011.30059, ≤ 17.011.30199	no fix published	NVD

Adobe acrobat dcversion to verify

Branch	Affected	Fixed in	Source
21.5	≥ 15.008.20082, ≤ 21.005.20058	no fix published	NVD
21.5	≥ 15.008.20082, ≤ 21.005.20060	no fix published	NVD

Adobe acrobat readerversion to verify

Branch	Affected	Fixed in	Source
20.x	≥ 20.001.30005, ≤ 20.004.30006	no fix published	NVD
17.11	≥ 17.011.30059, ≤ 17.011.30199	no fix published	NVD

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.

Fix

Advisories and patches

helpx.adobe.comRelease Notes · Vendor Advisory

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

CNACVSS 3.17.8read 2026-10-23
NVDCVSS 2.06.8read 2026-10-23
CNAweakness (CWE)CWE-787read 2026-10-23
FIRST EPSSEPSS score76.7 %read 2026-10-23

Technical details

CVSS v3 Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Published: 2021-09-29
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2021-39843?

Is CVE-2021-39843 actively exploited?

Active exploitation of CVE-2021-39843 has not been confirmed. Its EPSS score was 76.7% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-39843?

CVE-2021-39843 has a CVSS v3 base score of 7.8 (HIGH severity), with vector string CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

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