CVE-2026-126069: XSS (CVSS 4.7)

Description

Action View is a framework for handling view template lookup and rendering and provides view helpers for building HTML. Prior to 8.1.4.1 and 8.0.5.2, the fix for CVE-2026-33168 skips blank HTML attribute names in Action View tag helpers, but it tests the name before converting it to a string. A Symbol name made only of whitespace, such as :" ", is not blank, because Symbol#blank? is Symbol#empty?, so it reaches the attribute escaping, which emits an attribute with no name and produces malformed HTML. The asset tag helpers, such as image_tag, video_tag and audio_tag, symbolize their options, so a whitespace String name passed to them takes the same path. A carefully crafted attribute value could then be misinterpreted by the browser as a separate attribute name, possibly leading to XSS. Applications that allow users to specify custom HTML attribute names are affected. This issue is fixed in versions 8.1.4.1 and 8.0.5.2.

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CVSS v3.1 Score

4.7

MEDIUM

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

EPSS — Exploit Prediction

0.0024

Probability of exploitation

0.15%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-79 Cross-site Scripting (XSS)

References

Other References

https://github.com/rails/rails/commit/9190210606ffe52f92fdc75637f8ff69404f22c8 https://github.com/rails/rails/commit/f47452533e1f28d847c63181b9d5f8b7243ef9a4 https://github.com/rails/rails/releases/tag/v8.0.5.2 https://github.com/rails/rails/releases/tag/v8.1.4.1 https://github.com/rails/rails/security/advisories/GHSA-68p9-83h6-5wpj

Frequently Asked Questions

What is CVE-2026-126069? +

Action View is a framework for handling view template lookup and rendering and provides view helpers for building HTML. Prior to 8.1.4.1 and 8.0.5.2, the fix for CVE-2026-33168 skips blank HTML attribute names in Action View tag helpers, but it tests the name before converting it to a string. A Symbol name made only of whitespace, such as :" ", is not blank, because Symbol#blank? is Symbol#empty?, so it reaches the attribute escaping, which emits an attribute with no name and produces malformed HTML. The asset tag helpers, such as image_tag, video_tag and audio_tag, symbolize their options, so a whitespace String name passed to them takes the same path. A carefully crafted attribute value could then be misinterpreted by the browser as a separate attribute name, possibly leading to XSS. Applications that allow users to specify custom HTML attribute names are affected. This issue is fixed in versions 8.1.4.1 and 8.0.5.2. It has a CVSS v3.1 base score of 4.7 (MEDIUM).

How severe is CVE-2026-126069? +

CVE-2026-126069 has a CVSS v3.1 score of 4.7 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0024, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-126069? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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