CVE-2026-27169

High

Published: 21 February 2026

Published

21 February 2026

Modified

23 February 2026

KEV Added

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Patch

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CVSS Score 8.9 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:L

EPSS Score 0.0002 6.2th percentile

Risk Priority 18 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2026-27169 is a high-severity Cross-site Scripting (CWE-79) vulnerability in Opensift Opensift. Its CVSS base score is 8.9 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique JavaScript (T1059.007); ranked at the 6.2th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

This vulnerability is AI-related — categorised as Machine Learning Libraries.

The strongest mitigations our analysis identified are NIST 800-53 SI-15 (Information Output Filtering) and SI-2 (Flaw Remediation).

Threat & Defense at a Glance

What attackers do: exploitation maps to JavaScript (T1059.007) and 3 other techniques. What defenders deploy: see the NIST 800-53 controls recommended below.

Threat & Defense Details

Mitigating Controls (NIST 800-53 r5)AI

SI-15 Information Output Filtering good match

prevent

SI-15 directly addresses unsafe HTML interpolation by requiring filtering of untrusted user/model content prior to rendering in UI surfaces to block XSS script execution.

SI-10 Information Input Validation partial match

prevent

SI-10 validates information inputs from users or AI models before storage in study/quiz/flashcard content, preventing injection of malicious XSS payloads.

SI-2 Flaw Remediation good match

prevent

SI-2 ensures timely flaw remediation by applying the specific XSS fix released in OpenSift version 1.1.3-alpha.

MITRE ATT&CK Enterprise TechniquesAI

T1059.007 JavaScript Execution

Adversaries may abuse various implementations of JavaScript for execution.

attack.mitre.org →

T1185 Browser Session Hijacking Collection

Adversaries may take advantage of security vulnerabilities and inherent functionality in browser software to change content, modify user-behaviors, and intercept information as part of various browser session hijacking techniques.

attack.mitre.org →

T1189 Drive-by Compromise Initial Access

Adversaries may gain access to a system through a user visiting a website over the normal course of browsing.

attack.mitre.org →

T1539 Steal Web Session Cookie Credential Access

An adversary may steal web application or service session cookies and use them to gain access to web applications or Internet services as an authenticated user without needing credentials.

attack.mitre.org →

Why these techniques?

Stored XSS enables arbitrary JavaScript execution in authenticated browser sessions (T1059.007), directly supporting browser session hijacking (T1185) and web session cookie theft (T1539). The web app context with user-generated tainted content also facilitates drive-by compromise against victims viewing the content (T1189).

Confidence: MEDIUM · MITRE ATT&CK Enterprise v18.1

NVD Description

OpenSift is an AI study tool that sifts through large datasets using semantic search and generative AI. Versions 1.1.2-alpha and below render untrusted user/model content in chat tool UI surfaces using unsafe HTML interpolation patterns, leading to XSS. Stored content…

can execute JavaScript when later viewed in authenticated sessions. An attacker who can influence stored study/quiz/flashcard content could trigger script execution in a victim’s browser, potentially performing actions as that user in the local app session. This issue has been fixed in version 1.1.3-alpha.

Deeper analysisAI

CVE-2026-27169 is a cross-site scripting (XSS) vulnerability affecting OpenSift, an AI study tool that uses semantic search and generative AI to process large datasets. Versions 1.1.2-alpha and below render untrusted user or model-generated content in chat tool UI surfaces via unsafe HTML interpolation patterns. This improper encoding (CWE-116, CWE-79) allows stored content to execute arbitrary JavaScript when viewed in authenticated sessions. The vulnerability was published on 2026-02-21 and carries a CVSS v3.1 base score of 8.9 (AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:L).

An attacker requires low privileges (PR:L) to influence stored study, quiz, or flashcard content, such as by injecting malicious payloads via user inputs or AI-generated outputs. Exploitation occurs over the network (AV:N) with low complexity when a victim with an authenticated session views the tainted content, requiring user interaction (UI:R). Successful attacks trigger JavaScript execution in the victim's browser with changed scope (S:C), enabling high-impact actions like data exfiltration (C:H), session manipulation (I:H), or limited disruption (A:L) as the victim within the local app session.

The issue is fixed in OpenSift version 1.1.3-alpha. Mitigation details are available in the GitHub release notes at https://github.com/OpenSift/OpenSift/releases/tag/v1.1.3-alpha and the security advisory at https://github.com/OpenSift/OpenSift/security/advisories/GHSA-qrpx-7cmv-5gv5, which practitioners should review for upgrade instructions and any interim workarounds.