CVE-2026-34621
Acrobat Reader versions 24.001.30356, 26.001.21367 and earlier are affected by an Improperly Controlled Modification of Object Prototype Attributes ('Prototype…
- Severity
- 8.6 / 10
- High · CVSS 3.1
- Exploit chance (EPSS)
- 7.23%
- Chance of exploitation in the next 30 days. Higher than 94.33% of scored vulnerabilities.
- Known exploited
- Yes
- In CISA's catalog since Apr 13, 2026
- Weakness
- CWE-1321 Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
- Fix
- None yet
- No fixed version published
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.
How to fix
No fixed version has been published yet. Until one is, remove or replace the package, or turn off or isolate the affected feature. This page updates when a fix ships.
Severity breakdown
CVSS 3.1 8.6
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
- Attack vector
- Local
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- Required
- Scope
- Changed
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Weakness
CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.
How to prevent it
- Implementation: By freezing the object prototype first (for example, Object.freeze(Object.prototype)), modification of the prototype becomes impossible.
- Architecture and Design: By blocking modifications of attributes that resolve to object prototype, such as proto or prototype, this weakness can be mitigated.
- Implementation: When handling untrusted objects, validating using a schema can be used.
- Implementation: By using an object without prototypes (via Object.create(null) ), adding object prototype attributes by accessing the prototype via the special attributes becomes impossible, mitigating this weakness.
- Implementation: Map can be used instead of objects in most cases. If Map methods are used instead of object attributes, it is not possible to access the object prototype or modify it.
References
Advisories
Other links
Timeline
- Published
- Added to CISA's Known Exploited Vulnerabilities catalog
- Remediation due for U.S. federal agencies
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-6wvx-3r32-xmcg Forge: Prototype Pollution in forge.http cookie handling via a malicious Set-Cookie | Medium | Same weakness, CWE-1321 |
| GHSA-7648-jmwf-vw7j systeminformation has prototype pollution in `networkStats()` via the interface name | Medium | Same weakness, CWE-1321 |
| GHSA-m2m5-rw3w-cwmj ApostropheCMS: Client-side Prototype Pollution in apos.http.parseQuery leading to DOM-based XSS against authenticated users | Medium | Same weakness, CWE-1321 |
| GHSA-j5rq-xfvr-p969 ApostropheCMS: Authenticated projection-exclusion prototype-member deletion in @apostrophecms/db-connect causes process-wide denial of service | High | Same weakness, CWE-1321 |
| GHSA-97rh-rhh2-7vjv Payload: Remote Code Execution through first-register | High | Same weakness, CWE-1321 |
| GHSA-4q55-j62x-fr9h devalue: Malformed null-prototype object keys bypass __proto__ rejection via property-key coercion | Medium | Same weakness, CWE-1321 |
| GHSA-x97p-jq2g-jp4f Axios: Prototype Pollution Gadget in axios toFormData Options | High | Same weakness, CWE-1321 |
| GHSA-vh66-26gq-q6x8 Axios: Prototype pollution gadget in fetch adapter can alter outbound requests | Medium | Same weakness, CWE-1321 |
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