Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:NCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2026-23839 is a critical-severity Improper Input Validation (CWE-20) vulnerability in Leepeuker Movary. Its CVSS base score is 9.3 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Browser Session Hijacking (T1185); ranked at the 19th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-23839 is a cross-site scripting (XSS) vulnerability in Movary, a self-hosted web application for tracking, rating, and exploring movie watch history. The issue stems from insufficient input validation (CWE-20) in the `?categoryUpdated=` parameter, allowing attackers to inject and trigger arbitrary JavaScript payloads. It affects all versions of Movary prior to 0.70.0 and has a CVSS v3.1 base score of 9.3 (AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N), indicating high severity due to its network accessibility, low attack complexity, lack of required privileges, and potential for high confidentiality and integrity impacts in a scoped context (CWE-79).
Remote attackers without authentication can exploit this vulnerability by crafting malicious URLs or inputs that include XSS payloads in the `?categoryUpdated=` parameter. Exploitation requires user interaction, such as a victim clicking a specially crafted link or visiting a malicious page while logged into a vulnerable Movary instance. Successful attacks enable theft of sensitive user data, such as session cookies or personal watch history, session hijacking, or unauthorized modifications to the application's client-side state.
The Movary project addressed the vulnerability in version 0.70.0, which includes a fix for input validation. Security practitioners should upgrade to this version or later. Official advisories and code details are available in the GitHub security advisory (GHSA-v32w-5qx7-p3vq), the release notes for v0.70.0, and the affected JavaScript file at public/js/settings-account-location.js line 237.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-3302
Vulnerability Data
Movary is a web application to track, rate and explore your movie watch history. Due to insufficient input validation, attackers can trigger cross-site scripting payloads in versions prior to 0.70.0. The vulnerable parameter is `?categoryUpdated=`. Version 0.70.0 fixes the issue.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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- 6 hardening rules · 3 OS baselines
V1.1.2V1.3.2
Mitigating Controls (NIST 800-53 r5) AI
Developer testing and evaluation can discover missing input validation through analysis or test cases.
SI-10 directly requires validity checks on information inputs, structurally preventing improper or missing validation.
Output filtering can catch or sanitize unneutralized script content before it is served to users.
Requiring documented development standards and tools can embed input-validation practices into the engineering process.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly require and enforce input validation during development.
Patching and EOL replacement can remediate known XSS instances in libraries or frameworks (partial) but do nothing to enforce input neutralization in application code (none).
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Testing against a defined set of requirements and using code review plus vulnerability scanning forces validation of inputs and handling of unanticipated conditions, reducing the chance that malformed data will be accepted.
Knowledge exchange on emerging attack techniques and patches reduces the likelihood that cross-site scripting flaws remain unaddressed in deployed applications.
Operational indicators of compromise for web-application attacks can be incorporated into WAF or input-filtering rules, lowering the likelihood that unsanitized data reaches the browser.
Secure-coding guidelines and mandatory security testing (including code scans) compel developers to validate and sanitize inputs at design and implementation time, lowering the incidence of malformed or malicious data reaching downstream components.
Mandating input controls that include integrity checks and input validation ensures that untrusted data is examined before use, blocking the root cause of many injection and malformed-data weaknesses.
Security-by-design principles explicitly call for data validation and sanitization at every layer, reducing the chance that malformed or malicious input will be processed without scrutiny.
Hardening callouts derived
Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).
RHEL 8 (1 rule)
- V-230265 RHEL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-20