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Advisory record · GHSA-vcc4-2c75-vc9v

Caddy: stripHTML template function bypass

CVSS 4.2 MediumEPSS 0.0025 · 16th percentile

Published by the GitHub Advisory Database at 16 Jun 2026, 21:28 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
github.com/caddyserver/caddy/v2Go<2.11.42.11.4
github.com/caddyserver/caddyGo<=1.0.5No fixed version yet
Identifiers
GHSA-vcc4-2c75-vc9v · CVE-2026-52846 · GO-2026-5660
Weakness (CWE)
CWE-116
Tags
Published
16 Jun 2026
Updated
24 Jul 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Caddy's stripHTML template function (github.com/caddyserver/caddy/v2 versions before 2.11.4) can fail to remove all HTML tags from malformed input, so some markup survives. If a template then renders that output as HTML, an attacker who controls the input could cause client-side cross-site scripting. Upgrade to version 2.11.4. The legacy github.com/caddyserver/caddy package, versions up to 1.0.5, is also affected and no fixed version is listed for it.

Written 6 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
4.2 Medium 3.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N CNA (GitHub_M)
  • CISA KEV Not listed.
  • EPSS 0.0025, the 16th percentile, on 6 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 14:56 UTC First seen by agentprime
  2. 31 Oct 2026, 14:56 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.