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ExploitedIn CISA KEVFix available

CVE-2021-28550

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

  • Published2021-09-02
  • WeaknessCWE-416

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 2021.001.20150 (and earlier), 2020.001.30020 (and earlier) and 2017.011.30194 (and earlier) are affected by a Use After Free 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. 2021-09-0217:15CVE 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. 2025-02-0418:17SSVC exploitation set to activeCISA-ADP

Observed activity

isMalicious corpus · updated 2026-11-04 09:37 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-2021-28550?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-28550?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
17.11≥ 17.011.30059, ≤ 17.011.30194no fix published
20.1≥ 20.001.30005, ≤ 20.001.30020no fix published
Adobe acrobat dcversion to verify
BranchAffectedFixed in
21.1≥ 15.008.20082, ≤ 21.001.20150no fix published
21.1≥ 15.008.20082, ≤ 21.001.20149no fix published
Adobe acrobat readerversion to verify
BranchAffectedFixed in
17.11≥ 17.011.30059, ≤ 17.011.30194no fix published
20.1≥ 20.001.30005, ≤ 20.001.30020no 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
    • ≤ 2020.001.30020no fix statedcustom
    • ≤ 2021.001.20150no fix statedcustom
    • ≤ 2017.011.30194no fix statedcustom
    • ≤ Noneno fix statedcustom

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2023-03-28

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • torCleanStartall versions · fixed in 0.4.6.5-r0
  • torAlpine:v3.24all versions · fixed in 0.4.6.5-r0
  • torAlpine:v3.23all versions · fixed in 0.4.6.5-r0
  • torAlpine:v3.22all versions · fixed in 0.4.6.5-r0
  • torAlpine:v3.21all versions · fixed in 0.4.6.5-r0
  • torAlpine:v3.20all versions · fixed in 0.4.6.5-r0
  • torAlpine:v3.19all versions · fixed in 0.4.6.5-r0
  • torAlpine:v3.18all versions · fixed in 0.4.6.5-r0

5 more package ranges on OSV.dev

Full record on NVD

Fix

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

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
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
2021-09-02
Last Modified
2026-06-17
NVD status
Analyzed
GitHub Advisory
GHSA-865h-4rjv-52pg

Frequently asked questions

What is CVE-2021-28550?

Acrobat Reader DC versions versions 2021.001.20150 (and earlier), 2020.001.30020 (and earlier) and 2017.011.30194 (and earlier) are affected by a Use After Free 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-2021-28550 actively exploited?

Yes. CVE-2021-28550 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-2021-28550?

CVE-2021-28550 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