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Foxit PDF Editor EUVDEUVD-2026-85123

| CVE-2026-91805 HIGH
Use After Free (CWE-416)
2026-09-23 Foxit GHSA-w77c-2xq3-h9h8
7.8
CVSS 3.1 · Vendor: Foxit
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Craft PDF with malicious page-tree structure
  2. Delivery
    Deliver via email or web download
  3. Exploit
    Victim opens file in Foxit
  4. Execution
    Page-structure change frees page object during render
  5. Persist
    Access released object triggers UAF
  6. Impact
    Memory corruption / application crash

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Memory lifecycle management
MITRE ATT&CK

2 techniques across 2 tactics: Execution, Privilege Escalation

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Exploitation requires a victim to open an attacker-crafted PDF in Foxit PDF Editor or Reader; the malicious file must induce a page-structure change during rendering that frees a page object still in use (the page-tree handling flaw). Limiting factors: mandatory user interaction (UI:R) to open the file, local attack vector (AV:L - no remote/network-triggered path), and no authentication needed on the victim's side. There is no special product configuration required - it affects default document-rendering behavior - but the attack depends entirely on social engineering the user into opening the file.

Impact

This is a client-side file-parsing use-after-free (CWE-416) in Foxit PDF Editor/Reader. The CVSS 3.1 vector (AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H = 7.8) is the standard 'open a malicious document' profile: local attack vector because the victim must open a file, no privileges required, but mandatory user interaction (UI:R). Note a discrepancy worth flagging: the vendor rates full C:H/I:H/A:H impact (implying code execution is achievable, which is plausible for a controllable UAF), yet the description itself only claims 'memory corruption and an application crash' (i.e., a DoS). The impact metrics reflect worst-case exploitability rather than what the text demonstrates - verify with Foxit whether reliable code execution is confirmed. On real-world signals: no EPSS score is provided, there is no CISA KEV listing, and no public POC is referenced (only the vendor security-bulletins index). So despite the 7.8 'High' rating, there is no evidence of active exploitation or a weaponized exploit at this time; risk is gated behind social-engineering a user into opening a crafted PDF. This is a real patch-worthy issue for a widely-deployed reader, but not an emergency drop-everything item absent exploitation evidence.

Exploit ScenarioDerived

An attacker emails or hosts a specially crafted PDF that mutates its page-tree structure during rendering; when a victim opens it in Foxit PDF Reader/Editor, the application accesses freed page objects, corrupting memory and crashing (with potential for code execution in the app's context). No public exploit code is identified at time of analysis, and exploitation requires the user to open the malicious file (UI:R).

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
No patch listed yet 0.2% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 23, 2026

Opening a malicious PDF in Foxit PDF Editor or Foxit PDF Reader can corrupt memory and terminate the application: the document forces a page-structure change while the file is being rendered, so the page-tree logic accesses a page object that has already been released (CWE-416, use-after-free). Rated CVSS 3.1 base 7.8 (AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H), the flaw requires no authentication on the victim's side but does require the user to open the crafted file, making social engineering the sole delivery gate. No public exploit code and no confirmed active exploitation were identified at time of analysis.

RemediationAI

No exact fixed version is specified in the supplied CVE data, so the primary action is to consult the Foxit security bulletins page (https://www.foxit.com/support/security-bulletins.html), identify the bulletin entry for CVE-2026-91805, and update Foxit PDF Editor and Foxit PDF Reader to the build(s) it names; because the CPE version fields are wildcards, do not assume an unpatched-looking build number is safe without checking the bulletin. Interim compensating controls, with their trade-offs: enable Foxit's Protected View / Safe Reading Mode so documents render in a restricted context that limits what a corrupted render pass can reach (users lose interactive document features such as embedded scripts, links and some form behaviour); deploy the reader inside an OS-level sandbox or low-integrity container (Windows AppContainer, App Sandbox on macOS) so a memory-corruption outcome cannot readily reach host resources, at the cost of file-association and printing convenience; and strip or quarantine PDF attachments inbound at mail and web gateways, or force download-and-review workflows instead of in-browser auto-open, which reduces the social-engineering surface but does not stop a determined user from opening the file. Note that disabling JavaScript does not address this defect - it is a page-tree lifetime bug triggered during rendering, not a script execution issue - so treat script-blocking as unrelated hardening rather than a mitigation. Monitor for vendor updates, as the pagination path is a common target for follow-on fixes.

Affected VersionsENISA

Foxit PDF Editor Versions 2026.2 and earlier
Foxit PDF Reader Versions 2026.2 and earlier
Foxit PDF Editor Versions 14.0.7 and earlier
Foxit PDF Editor Versions 13.2.6 and earlier

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

The root cause is a use-after-free (CWE-416) in the PDF page-tree handling layer of Foxit's rendering engine. A PDF's page tree (/Pages, /Kids, /Count nodes and their associated page objects) defines document pagination and is walked during layout and rendering; a crafted file can cause that structure to be mutated - pages added, removed or reassigned - while a render pass still holds a reference to a page object, so the freed object is dereferenced and memory is corrupted. The reported tags (buffer overflow, memory corruption, use-after-free) are consistent with a heap lifetime-management defect rather than an attacker-controlled write primitive on its own; on modern Windows builds the practical outcome observed is a crash, though the CVSS impact ratings of C:H/I:H/A:H reflect that memory corruption in a document parser is a plausible escalation path to code execution. CPE data maps the exposure to two products from Foxit Software Inc.: foxit_pdf_editor and foxit_pdf_reader, with the affected version range left unspecified ('*') in the supplied data, so the vendor bulletin must be consulted for exact fixed builds. The attack vector is local (AV:L) with required user interaction (UI:R) and no privileges (PR:N) - this is a classic client-side file-parsing bug, not a network-reachable service flaw.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (Foxit) PRIMARY 7.8 HIGH
AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
vuln.today AI 7.8 HIGH

Local file-open UAF: AV:L and UI:R because the victim must open a crafted PDF, PR:N as no auth is needed; retained vendor C/I/A:H for worst-case controllable UAF, though description substantiates only a crash.

3.1 AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
4.0 AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Primary rating from Vendor (Foxit).

CVSS VectorVendor: Foxit

Attack Vector
Local
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

DescriptionCVE.org

A use-after-free vulnerability exists in Foxit PDF Editor/Reader’s PDF page-tree handling. A specially crafted PDF can trigger page-structure changes during rendering, causing the application to access released page objects and resulting in memory corruption and an application crash.

Executive ViewAI

Why It Matters

Foxit PDF Editor and Foxit PDF Reader are affected by a high-severity memory corruption vulnerability that can be triggered when a user opens a specially crafted PDF, potentially leading to application crashes and possible further compromise of the affected system. No vendor-released patch identified at time of analysis, and no public exploit identified at time of analysis, but the risk is significant because the attack requires only that an employee open a malicious file. Leadership should ensure users avoid untrusted PDFs and consider temporary use of alternative PDF viewers to protect sensitive data and maintain business continuity.

Business Impact: High
Compensating Controls

No vendor-released patch identified at time of analysis. Interim mitigations include user education to avoid opening untrusted PDFs, email and web filtering to block malicious PDFs, using alternative PDF viewers for untrusted documents, enabling any available sandbox or protected mode features in Foxit, and monitoring for vendor patch release.

Threat Intelligence Overview

EPSS Score
0.2%
Top 93% exploitable
Prevalence
High
Foxit PDF Reader/Editor is a very popular free/commercial Adobe alternative, widely deployed on desktops
Data Quality
6 sources
Confidence: High

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS 0.2%
Patch available No
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision
Scheduled
Exploitation
None
System Exposure· derived
Small
Automatable
No
Human Impact
High
Technical Impact
Total

Priority Score

39
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +39
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.

Use-after-free vulnerabilities occur when a program continues to access memory through a pointer after that memory has been deallocated.

Memory corruption occurs when a program writes data beyond the boundaries of allocated memory regions or accesses memory in unintended ways, violating the integrity of the process's address space.

CVE-2026-91814 MEDIUM POC
5.3 Sep 23

Content spoofing in Foxit PDF Editor and Foxit PDF Reader allows remote attackers to alter visible content in incrementa

CVE-2026-91800 HIGH
8.8 Sep 23

Local privilege escalation in Foxit PDF Editor for macOS allows an attacker with a low-privilege foothold to execute arb

CVE-2026-91798 HIGH
8.8 Sep 23

A local privilege escalation vulnerability in the auto-update daemon shipped with Foxit PDF Editor and Foxit PDF Reader

CVE-2026-91812 HIGH
8.1 Sep 23

Man-in-the-middle attackers occupying the network path of Foxit PDF Editor and Foxit PDF Reader software-update traffic

CVE-2026-91797 HIGH
7.8 Sep 23

Path traversal in the attachment-handling logic of Foxit PDF Editor and Foxit PDF Reader lets a crafted PDF write an emb

CVE-2026-91794 HIGH
7.8 Sep 23

An out-of-bounds write (CWE-787) in the PDF rendering engine of Foxit PDF Editor and Foxit PDF Reader can be triggered w

CVE-2026-91789 HIGH
7.8 Sep 23

Out-of-bounds write in the U3D/GIF texture decoding path of Foxit PDF Editor and Foxit PDF Reader allows a crafted PDF t

CVE-2026-91801 HIGH
7.8 Sep 23

Insufficient validation of embedded-resource file paths in Foxit PDF Editor and Foxit PDF Reader (CVE-2026-91801) lets a

CVE-2026-91791 HIGH
7.8 Sep 23

Foxit PDF Editor and Reader can crash due to a use-after-free (CWE-416) when a user opens a specially crafted PDF that i

CVE-2026-91799 HIGH
7.8 Sep 23

Use-after-free in Foxit PDF Editor and Foxit PDF Reader (CWE-416) lets a specially crafted PDF trigger memory corruption

CVE-2026-91815 HIGH
7.8 Sep 23

Heap-based out-of-bounds write in Foxit PDF Editor and Foxit PDF Reader occurs when the products decode JPEG2000 image d

CVE-2026-91790 HIGH
7.8 Sep 23

A use-after-free in Foxit PDF Editor and Foxit PDF Reader can be triggered by opening a crafted PDF whose image objects

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