CVE-2026-57247: Foxit PDF Editor & Reader Use-After-Free Vulnerability – Analysis & Patch Guide

Technical summary

CVE-2026-57247 is a use-after-free flaw (CWE-416) affecting Foxit PDF Editor and PDF Reader. The root cause is a race condition in document field processing: the application re-enters the document structure during field handling, triggers deletion of the current page, and then dereferences field objects that were obtained before the deletion occurred. This results in reading from freed memory, causing an application crash. The CVSS 3.1 score of 7.8 (HIGH) reflects local attack vector, low complexity, no privilege requirement, and user interaction needed, with high impact to confidentiality, integrity, and availability.

Business impact

Organizations relying on Foxit PDF products for secure document handling face potential disruption. An attacker can distribute a malicious PDF that crashes the application when opened, causing denial of service to end users. In environments where PDFs are processed in batch workflows or by service accounts, repeated crashes could degrade operational efficiency. While the vulnerability does not appear to grant remote code execution outright, the use-after-free condition creates memory corruption that could be chained with other techniques to achieve privilege escalation or code execution, especially on systems with additional mitigations disabled.

Affected systems

Foxit PDF Editor and Foxit PDF Reader are the primary affected products. The vulnerability affects both Windows and macOS versions of these applications. Users should verify the specific version ranges impacted by consulting Foxit's security advisory. Other PDF readers and related tools are not known to be affected based on available information.

Exploitability

Exploitation requires local access and user interaction—a victim must open a malicious PDF file in Foxit PDF Editor or PDF Reader. The attack is not remotely exploitable and does not require elevated privileges. The low complexity of crafting a triggering PDF (compared to some memory corruption flaws) and the likelihood of end users opening PDFs from untrusted sources make this a realistic attack scenario. No known public exploit code or proof-of-concept is documented, but the technical details are straightforward enough that security researchers or threat actors could develop weaponized payloads.

Remediation

Apply the security patch provided by Foxit for both PDF Editor and PDF Reader. The exact patched versions should be confirmed through Foxit's official security advisory. Until patches are deployed, mitigations include: restricting PDF opening to trusted sources, disabling automatic PDF opening in browsers or email clients, running Foxit in a sandboxed environment, and educating users to avoid opening PDFs from unknown senders. Organizations with managed endpoints should prioritize patching through their patch management system.

Patch guidance

Contact Foxit directly or visit their security advisory page to identify the specific patched versions for your deployment (Editor and Reader may have different release schedules). Foxit typically publishes patches through their download portal and may offer automatic update prompts in newer versions. Test patches in a non-production environment first to ensure compatibility with workflows. If you manage PDFs via a document management system, verify that the system's integrated PDF handling does not depend on the vulnerable Foxit components.

Detection guidance

Monitor for Foxit PDF Editor and Reader process crashes or application hangs, especially when users report crashes after opening unexpected PDF attachments. Endpoint detection and response (EDR) tools should flag use-after-free patterns in memory access logs if configured for memory safety monitoring. Network sensors may not detect this vulnerability since it requires local file interaction, but email security gateways can apply sandboxing to execute suspicious PDFs and detect crashes. Correlate crash reports with PDF file submissions to identify patterns of malicious documents.

Why prioritize this

Although not yet on the CISA Known Exploited Vulnerabilities (KEV) catalog, this vulnerability merits high priority due to its HIGH CVSS score, ease of triggering via user interaction, and potential for memory corruption attacks. Foxit's large user base and the commonality of PDF-based attacks make this a likely target for threat actors. Organizations should treat this as a critical update within 2–4 weeks if operating a defense-in-depth posture.

Risk score, explained

The CVSS 3.1 score of 7.8 reflects: (1) local attack vector reducing remote risk but not eliminating supply-chain or physically-proximate threat scenarios; (2) no authentication or privilege escalation required; (3) user interaction necessary but realistic; (4) high impact across confidentiality, integrity, and availability due to memory corruption; and (5) use-after-free bugs historically serving as stepping stones to code execution. The score does not incorporate threat intelligence or real-world exploitation frequency, but the technical severity is substantial.

Frequently asked questions