What is the CVSS score of CVE-2026-27645?

CVE-2026-27645 has a CVSS 3.1 base score of 6.1 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N. EPSS exploitation probability: 0.0%.

Which versions of Flask are affected by CVE-2026-27645?

Organizations using versions should be aware of moderate risk from CVE-2026-27645, a cross-site scripting vulnerability rated CVSS 6.1.. A patch is available.

Is there a public PoC exploit available for CVE-2026-27645?

Yes, a public proof-of-concept exploit is available for CVE-2026-27645. Prioritise patching immediately. EPSS: 0.0%.

Flask CVE-2026-27645

MEDIUM

Cross-site Scripting (XSS) (CWE-79)

2026-02-25 security-advisories@github.com

GHSA-mw8m-398g-h89w

Flask Changedetection

6.1

CVSS 3.1 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

6.1 MEDIUM

AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

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

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Lifecycle Timeline

Analysis Generated

Mar 12, 2026 - 21:55 vuln.today

PoC Detected

Feb 25, 2026 - 16:51 vuln.today

Public exploit code

Patch released

Feb 25, 2026 - 16:51 nvd

Patch available

CVE Published

Feb 25, 2026 - 05:17 nvd

MEDIUM 6.1

DescriptionGitHub Advisory

changedetection.io is a free open source web page change detection tool. In versions prior to 0.54.1, the RSS single-watch endpoint reflects the UUID path parameter directly in the HTTP response body without HTML escaping. Since Flask returns text/html by default for plain string responses, the browser parses and executes injected JavaScript. Version 0.54.1 contains a fix for the issue.

AnalysisAI

changedetection.io versions before 0.54.1 are vulnerable to reflected cross-site scripting (XSS) via the RSS endpoint, where user-supplied UUID parameters are rendered without HTML encoding in text/html responses, allowing attackers to execute arbitrary JavaScript in users' browsers. Public exploit code exists for this vulnerability. …

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Vulnerability AssessmentAI

Risk Assessment	CVSS 6.1 (MEDIUM). … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario	An attacker could exploit this vulnerability to compromise the affected system.
Remediation	A vendor patch is available — apply it immediately. … Detailed patch versions, workarounds, and compensating controls in full report.

Recommended ActionAI

Within 30 days: Identify affected systems running versions and apply vendor patches as part of regular patch cycle. …

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CVE-2026-27645 vulnerability details – vuln.today

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