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GHSA-w67g-2h6v-vjgq

HighCVSS 7.1 / 10
Published Feb 6, 2026·Last modified Feb 6, 2026
Affected Components(0)

No affected components available

Description

Impact

During a security audit conducted with Claude Opus 4.6 and GPT-5.3-Codex, we identified three specific ways to bypass the XSS (cross-site-scripting) protection built into Phlex.

  1. The first bypass could happen if user-provided attributes with string keys were splatted into HTML tag, e.g. div(**user_attributes).
  2. The second bypass could happen if user-provided tag names were passed to the tag method, e.g. tag(some_tag_name_from_user).
  3. The third bypass could happen if user’s links were passed to href attributes, e.g. a(href: user_provided_link).

All three of these patterns are meant to be safe and all have now been patched.

Patches

Phlex has patched all three issues and introduced new tests that run against Safari, Firefox and Chrome.

The patched versions are:

Phlex has also patched the main branch in GitHub.

Workarounds

If a project uses a secure CSP (content security policy) or if the application doesn’t use any of the above patterns, it is not at risk.

Risk Scores
Base Score
7.1

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. The attacker needs the user to perform some action, like clicking a link. The impact is confined to the system where the vulnerability exists. There is a high impact on the confidentiality of the information. There is a low impact on the integrity of the data.

Threat Intelligence
6.5

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
N/A

Probability that this vulnerability will be exploited in the wild within the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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High severity
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