CASCACascade Atlas

Evidence dossier

CVE-2021-28550

Adobe Acrobat Reader use after free vulnerability could lead to arbitrary code execution

71.4–93.4Priority evidence range
As known Jul 19, 2026, 5:00 AM UTCgen-56ccdaf9

Normalized restatement

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.

State
PUBLISHED
Published
Sep 2, 2021
Updated
Oct 21, 2025
Evidence coverage
72%
CISA KEVCatalog member

Apply updates per vendor instructions.

FIRST EPSS52.01%

2026-07-18 · v2026.06.15 · percentile 98.8%

Source stateConflict visible

Distinct CVSS assessments remain side by side; none are averaged.

Source comparison

Who said what

adobeoriginal assertion
container

Adobe Acrobat Reader use after free vulnerability could lead to arbitrary code execution

CISA-ADPindependent enrichment
container

CISA ADP Vulnrichment

CVEderivative copy
container

CVE Program Container

CISA KEVoriginal assertion
observed_exploitation

Adobe Acrobat and Reader Use-After-Free Vulnerability

FIRST EPSSoriginal assertion
model_probability

Probability 0.520050000000; percentile 0.988340000000

Applicability

Cited product scope

Trace impact →
AdobeAcrobat Reader
[{"status": "affected", "version": "unspecified", "versionType": "custom", "lessThanOrEqual": "2020.001.30020"}, {"status": "affected", "version": "unspecified", "versionType": "custom", "lessThanOrEqual": "2021.001.20150"}, {"status": "affected", "version": "unspecified", "versionType": "custom", "lessThanOrEqual": "2017.011.30194"}, {"status": "affected", "version": "unspecified", "versionType": "custom", "lessThanOrEqual": "None"}]unknown
Unknown vendorUnknown product
cpe:2.3:a:adobe:acrobat:*:*:*:*:classic:*:*:*; start including 17.011.30059; end including 17.011.30194supported
Unknown vendorUnknown product
cpe:2.3:a:adobe:acrobat:*:*:*:*:classic:*:*:*; start including 20.001.30005; end including 20.001.30020supported
Unknown vendorUnknown product
cpe:2.3:a:adobe:acrobat_dc:*:*:*:*:continuous:*:*:*; start including 15.008.20082; end including 21.001.20150supported
Unknown vendorUnknown product
cpe:2.3:a:adobe:acrobat_dc:*:*:*:*:continuous:*:*:*; start including 15.008.20082; end including 21.001.20149supported
Unknown vendorUnknown product
cpe:2.3:a:adobe:acrobat_reader:*:*:*:*:classic:*:*:*; start including 17.011.30059; end including 17.011.30194supported
Unknown vendorUnknown product
cpe:2.3:a:adobe:acrobat_reader:*:*:*:*:classic:*:*:*; start including 20.001.30005; end including 20.001.30020supported
Unknown vendorUnknown product
cpe:2.3:a:adobe:acrobat_reader_dc:*:*:*:*:continuous:*:*:*; start including 15.008.20082; end including 21.001.20150supported
Unknown vendorUnknown product
cpe:2.3:a:adobe:acrobat_reader_dc:*:*:*:*:continuous:*:*:*; start including 15.008.20082; end including 21.001.20149supported
Unknown vendorUnknown product
cpe:2.3:o:apple:macos:-:*:*:*:*:*:*:*constrained
Unknown vendorUnknown product
cpe:2.3:o:apple:macos:-:*:*:*:*:*:*:*constrained
Unknown vendorUnknown product
cpe:2.3:o:microsoft:windows:-:*:*:*:*:*:*:*constrained
Unknown vendorUnknown product
cpe:2.3:o:microsoft:windows:-:*:*:*:*:*:*:*constrained

Assessments

CVSS by origin

8.8
nvd@nist.govCVSS 3.1 · role PrimaryCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
6.8
nvd@nist.govCVSS 2.0 · role PrimaryAV:N/AC:M/Au:N/C:P/I:P/A:P
9.6
psirt@adobe.comCVSS 3.0 · role SecondaryCVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
9.6
adobeCVSS 3.0 · role unknownCVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

Limitations and unknowns

  • KEV membership is authoritative for the catalog, not proof of exposure in any environment.
  • EPSS is a dated model probability and not an individual-environment prediction.
  • Affected or fixed status applies only to the exact cited product and version scope; unresolved scope remains unknown.
  • NVD-carried upstream facts remain derivative and are not independent corroboration.
  • Only NVD metrics validated under the generation-bound calculator are Public Priority eligible; direct CVE record metrics remain display-only.
  • NVD CVSS source eligibility is closed: NVD-authored, exact record-source, or registered same-CVE container origin; unmapped sources remain display-only.
  • Factor D is unknown in Public Core because no accepted canonical mapping-obligation ledger is present.
  • Core replay supports the active and immediately prior generation; retrospective valid-at replay is deferred.