VulnerabilityPublished 25 Feb 2026

CVE-2026-27645: dgtlmoon changedetection.io · Cross-site Scripting

Affects dgtlmoon changedetection.ioSource CVE Database V5

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Not known to be exploited · public detection template (Nuclei) · CVSS 6.1 Medium : upgrade to 0.54.1 when convenient.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 3.1 base score

6.1Medium

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

EPSS: 0.4% chance of exploitation in 30 days – higher than 42% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 0.54.1

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

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: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
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 25 Feb 2026
Detectable: evidence found.
nuclei template: Changedetection.io RSS Single Watch - Cross-Site Scripting
Weaponized: 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 29 Oct 2026.

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.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity 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

Upgrade changedetection.io and dgtlmoon/changedetection.io to 0.54.1.

Affected software

Product	Affected	Fixed in
dgtlmoonchangedetection.io	Affected <0.54.1	Fixed in 0.54.1
GitHubdgtlmoon/changedetection.io`pkg:github/dgtlmoon/changedetection.io`Other threats	Affected <0.54.1	Fixed in 0.54.1

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade changedetection.io to version 0.54.1 or later, where the vulnerability has been fixed by proper HTML escaping of the UUID parameter.
If immediate upgrade is not possible, implement web application firewall (WAF) rules to detect and block suspicious input patterns in the UUID path parameter, especially those containing script tags or JavaScript event handlers.
Employ Content Security Policy (CSP) headers to restrict execution of inline scripts and reduce the impact of potential XSS attacks.
Educate users and administrators about the risks of clicking on untrusted URLs, especially those containing unusual parameters.
Review and sanitize all user-controllable inputs in custom deployments or integrations of changedetection.io to ensure no unescaped data is reflected in HTML responses.
Monitor logs for unusual access patterns to the RSS single-watch endpoint that may indicate attempted exploitation.
Conduct regular security assessments and code reviews focusing on input validation and output encoding in web applications.

Description

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.

Impact

The primary impact of CVE-2026-27645 is on the confidentiality and integrity of users interacting with the vulnerable changedetection.io instance. An attacker can craft malicious URLs that, when visited by a user, execute arbitrary JavaScript in the victim's browser context. This can lead to theft of sensitive information such as session tokens, cookies, or other data accessible via the browser, and manipulation of client-side content or behavior. While the vulnerability does not affect the availability of the service, the compromise of user data or session integrity can lead to further attacks such as account takeover or unauthorized actions. Organizations relying on changedetection.io for monitoring web content changes may inadvertently expose their users or administrators to these risks if running vulnerable versions. Since exploitation requires user interaction, phishing or social engineering campaigns could be used to lure victims to malicious URLs. The scope of affected systems is limited to installations of changedetection.io versions prior to 0.54.1, but given the open-source nature and potential deployment in diverse environments, the impact can be widespread if not mitigated.

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

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 25 Feb 2026, 05:11 UTC

Public exploits and detectiona Nuclei detection template

WeaknessesCWE-79

Technical details

References

Community reviews

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