Acrobat Reader | Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') (CWE-1321) (CVE-2026-34621) | HOL Guard CVE

High · CVSS 8.6Known ExploitedCVE-2026-34621

Acrobat Reader | Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') (CWE-1321)

Answer in brief

CVE-2026-34621 records a High severity (CVSS 8.6) vulnerability in Acrobat Reader | Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') (CWE-1321). The current sources mark it as known exploited. The current feed maps Adobe/Acrobat 2024 (generic), Adobe/Acrobat DC (generic), Adobe/Acrobat Reader (generic), Adobe/Acrobat Reader DC (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Apr 11, 2026Updated Aug 28, 2026Source checked Sep 21, 2026First seen by HOL May 24, 2026Material review Aug 28, 2026

Upstream Advisory

Key facts

Risk: High · CVSS 8.6
Exploitation: Known exploited
Affected software: 9 mapped packages or products
Fix availability: Not reported

Why this deserves its current priority

CVSS is 8.6. Known-exploitation status makes exposure review time-sensitive. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Adobe/Acrobat 2024 (generic), Adobe/Acrobat DC (generic), Adobe/Acrobat Reader (generic), Adobe/Acrobat Reader DC (generic). Check affected ranges and fixed versions before updating.

Affected products and reported versions
Product	Affected versions	Fixed versions
cpe:2.3:a:adobe:acrobat:::::classic:::*	Not reported	Not reported
cpe:2.3:a:adobe:acrobat_dc:::::continuous:::*	Not reported	Not reported
cpe:2.3:a:adobe:acrobat_reader_dc:::::continuous:::*	Not reported	Not reported
cpe:2.3:o:apple:macos:-:::::::*	Not reported	Not reported
cpe:2.3:o:microsoft:windows:-:::::::*	Not reported	Not reported

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Adobe/Acrobat 2024generic	0	Not reported
Adobe/Acrobat DCgeneric	0	Not reported
Adobe/Acrobat Readergeneric	0	Not reported
Adobe/Acrobat Reader DCgeneric	0	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Adobe/Acrobat 2024, Adobe/Acrobat DC, Adobe/Acrobat Reader.
Review the reported fix. Monitor this advisory for an available fix and review any installs of the affected package.

Evidence timeline and material changes

Published upstream
Apr 11, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Aug 28, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
May 24, 2026
Added to CISA KEV
Apr 13, 2026
Evidence: source:kev:kev:kev:record

Sources and claim methodology

Upstream source description

Acrobat Reader versions 24.001.30356, 26.001.21367 and earlier are affected by an Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') 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.

Quoted source text, attributed separately from HOL analysis.