CVE-2026-1591VulnerabilityPublished 3 Feb 2026

CVE-2026-1591: pdfonline.foxit.com · XSS or 'Cross-site Scripting'

Affects pdfonline.foxit.comSource CVE Database V5

Not known to be exploited · CVSS 6.3 Medium.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.1 base score

6.3Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.2% chance of exploitation in 30 days – higher than 13% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

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

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 3 Feb 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
Foxit Software Inc.pdfonline.foxit.com	Affected =before 2026‑02‑03	Fixed in–

AI-suggested

European organizations should immediately verify if they use pdfonline.foxit.com and ensure their instances or accounts are updated to versions released after 2026-02-03 that address this vulnerability. If patching is not immediately possible, implement strict input validation and output encoding on any user-generated content displayed in the application, particularly usernames and file metadata. Employ Content Security Policies (CSP) to restrict the execution of inline scripts and limit sources of executable code, reducing the impact of potential XSS payloads. Educate users to be cautious when interacting with file upload lists and suspicious usernames. Monitor logs for unusual upload activity or attempts to inject scripts. Additionally, enforce strong authentication controls and session management to reduce the risk of credential compromise. Organizations should also consider isolating or sandboxing the affected application components to limit script execution privileges. Regular security assessments and penetration testing focused on web application vulnerabilities can help detect similar issues proactively.

Description

CVE-2026-1591 is a stored cross-site scripting (XSS) vulnerability in Foxit PDF Editor Cloud's file upload feature (pdfonline.foxit.com) affecting versions before 2026-02-03. The vulnerability arises because malicious usernames embedded in uploaded file lists are not properly escaped, allowing arbitrary JavaScript execution when the list is viewed. Exploitation requires authenticated access and some user interaction, with a medium severity CVSS score of 6.3. While no known exploits are currently in the wild, successful attacks could lead to theft of sensitive information or session hijacking. European organizations using this cloud-based PDF editor should prioritize patching or mitigating this vulnerability to prevent potential client-side attacks. Countries with high adoption of Foxit products and significant cloud service usage, such as Germany, France, and the UK, are most likely to be affected. Mitigation includes applying vendor patches when available, restricting user input, and employing Content Security Policies to limit script execution.

Impact

For European organizations, this vulnerability poses a risk primarily to confidentiality and user trust. If exploited, attackers could execute malicious scripts in the context of authenticated users, potentially stealing sensitive information such as session cookies, personal data, or corporate documents accessible via the cloud service. This could lead to unauthorized access to organizational resources or further lateral attacks. The integrity impact is lower but could involve manipulation of displayed content or user interface elements, potentially misleading users. Availability is not directly affected. Given the cloud nature of the service, the attack surface includes any European entity using Foxit PDF Editor Cloud, especially those handling sensitive or regulated data. This could have compliance implications under GDPR if personal data is compromised. The requirement for authenticated access and user interaction limits the attack scope but does not eliminate risk, especially in environments with many users or shared credentials. The medium severity rating suggests a moderate but actionable threat level.

Summary

CVE-2026-1591 is a stored cross-site scripting (XSS) vulnerability identified in Foxit Software Inc.'s cloud-based PDF editor service, pdfonline.foxit.com. The flaw exists in the file upload feature where the username associated with an uploaded file is embedded into the upload file list without proper input sanitization or escaping. This improper neutralization of input (CWE-79) allows an attacker to inject arbitrary JavaScript code that executes in the context of the victim's browser when the upload list is rendered. The vulnerability affects all versions of pdfonline.foxit.com prior to the fix released on 2026-02-03. Exploitation requires the attacker to have authenticated access to upload files with malicious usernames, and victims must view the affected upload list for the script to execute. The CVSS 3.1 base score is 6.3, reflecting a medium severity with network attack vector, low attack complexity, requiring privileges and user interaction, and impacting confidentiality highly while integrity is impacted to a lesser extent. Although no exploits have been reported in the wild, the vulnerability could be leveraged to steal session tokens, perform actions on behalf of users, or conduct phishing attacks within the trusted domain. The root cause is insufficient input validation and output encoding in the web application’s rendering logic for user-supplied data. This vulnerability highlights the importance of secure coding practices in cloud-based document management services.

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (opens in a new tab)
Base weaknessLikelihood of exploit: HighCWE Top 25 (2025): #1OWASP Top 10 A05:2025: Injection (opens in a new tab)
The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Implementation · Architecture and Design
Understand the context in which your data will be used and the encoding that will be expected. This is especially important when transmitting data between different components, or when generating outputs that can contain multiple encodings at the same time, such as web pages or multi-part mail messages.
Architecture and Design · Implementation · Attack Surface Reduction
Understand all the potential areas where untrusted inputs can enter your software: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide…
OWASP Cheat Sheets
Cross Site Scripting Prevention (opens in a new tab)
DOM based XSS Prevention (opens in a new tab)
Injection Prevention (opens in a new tab)
Abuse Case (opens in a new tab)
Deserialization (opens in a new tab)
OWASP ASVS 4.0.3
V5.3.3 (opens in a new tab)
V1.5.1 (opens in a new tab)
Attack patterns
XSS Using MIME Type Mismatch (opens in a new tab)
DOM-Based XSS (opens in a new tab)
Reflected XSS (opens in a new tab)
Stored XSS (opens in a new tab)
Cross-Site Scripting (XSS) (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

foxit.com/support/security-bulletins.html (opens in a new tab)

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 10 Feb 2026, 10:59 UTC

WeaknessesCWE-79

Technical details

References

Community reviews

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