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Response snapshot Oct 27, 2026, 04:52 UTC

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VulnerabilityCVE-2026-34621Known exploitation

Adobe Acrobat and Reader Prototype Pollution Vulnerability

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.

At a glance

Exploited
Yes: on CISA's Known Exploited list
Severity
8.6 High (CVSS 3.1)
Chance of exploitation
7.2% in the next 30 days
CISA federal deadline
Apr 27, 2026: passed
Sources
4 independent sources

What to do

Check the vendor advisory for affected versions and fixes.

CISA's required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Read NVD CVE-2026-34621 (opens a new tab)

What happened

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.

CISA federal deadline

Federal due date passed

Applies to covered US federal agencies; it is not your organization's deadline.

Added to the catalog Known ransomware use: Unknown
CISA catalog (opens a new tab)

Scores and how they were measured

CVSS base severity

8.6

Version 3.1As of

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

7.2%

Scored Percentile 94.3%

Model and measurement source (opens a new tab)

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    NVD CVE-2026-34621 (opens a new tab)

    NVD record: description, CVSS, affected products, and a CISA SSVC assessment reporting active exploitation.

    Published Checked

  2. Primary source

    Vendor advisory (via NVD references) (opens a new tab)

    The vendor advisory referenced by the CVE record, for affected versions and fixes.

    Published Date not suppliedChecked

  3. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  4. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  5. Primary source

    CISA KEV entry CVE-2026-34621 (opens a new tab)

    The CVE-2026-34621 catalog entry establishes known exploitation, date added, required action, and the federal due date; not zero-day status.

    Published Checked

  6. Primary source

    FIRST measured EPSS score (opens a new tab)

    Measured EPSS probability and percentile for CVE-2026-34621, scored 2026-10-26. This is a model estimate, not proof of exposure.

    Published Checked

  7. Primary source

    CVE Program CNA adobe (opens a new tab)

    The published CVE-2026-34621 document's CNA supplies this CVSS 3.1 base score, vector, and authoritative source update date.

    Published Checked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 26). Adobe Acrobat and Reader Prototype Pollution Vulnerability (CVE-2026-34621). https://kevwire.com/record/CVE-2026-34621

MLA

"Adobe Acrobat and Reader Prototype Pollution Vulnerability (CVE-2026-34621)." KEVWire, 26 Oct. 2026, kevwire.com/record/CVE-2026-34621.

Chicago

KEVWire. "Adobe Acrobat and Reader Prototype Pollution Vulnerability (CVE-2026-34621)." Last modified October 26, 2026. https://kevwire.com/record/CVE-2026-34621.

Evidence summary (plain text)

Adobe Acrobat and Reader Prototype Pollution Vulnerability (Apr 11, 2026).
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.
CVSS 8.6 (version 3.1; evidence as of Aug 27, 2026; https://cveawg.mitre.org/api/cve/CVE-2026-34621).
EPSS 7.2% for the following 30 days, scored Oct 26, 2026 (https://api.first.org/data/v1/epss?cve=CVE-2026-34621&date=2026-10-26).
Sources:
NVD CVE-2026-34621: https://nvd.nist.gov/vuln/detail/CVE-2026-34621
Vendor advisory (via NVD references): https://helpx.adobe.com/security/products/acrobat/apsb26-43.html
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-26T20:37:18.143Z&lastModEndDate=2026-10-26T22:10:56.995Z&resultsPerPage=500&startIndex=500
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-26T20:05:59.720Z&lastModEndDate=2026-10-26T21:35:56.549Z&resultsPerPage=500&startIndex=500
CISA KEV entry CVE-2026-34621: https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json
FIRST measured EPSS score: https://api.first.org/data/v1/epss?cve=CVE-2026-34621&date=2026-10-26
CVE Program CNA adobe: https://cveawg.mitre.org/api/cve/CVE-2026-34621
Record ID: CVE-2026-34621.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Documented by a cited source.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
CISA federal due date: Apr 27, 2026. This is a deadline for covered US federal agencies, not the reader's SLA.
About this data

This record was ingested from a data source. Retrieved: Oct 27, 2026, 01:40 UTC. Ingestion is not an independent editorial investigation.

NVD status: Analyzed. Publication in the NVD is not evidence of exploitation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

Record JSON

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Record details

Record detail