---
id: CVE-2026-45135
title: >-
  caddy: github.com/caddyserver/caddy/v2: Caddy: Remote Code Execution via
  Unsafe Unicode Handling in FastCGI (CVE-2026-45135)
summary: >-
  A flaw was found in Caddy. This vulnerability stems from unsafe handling of
  Unicode characters within the FastCGI component, specifically when processing
  request paths containing non-ASCII bytes. An attacker capable of placing
  content into…
severity: high
cvss: 8.1
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H'
cvssSource: vendor
cwe: CWE-1289
vendor: Red Hat
product: github.com/caddyserver/caddy/v2
affected:
  - 'github.com/caddyserver/caddy/v2 >= 2.7.0, < 2.11.3'
patched:
  - github.com/caddyserver/caddy/v2 2.11.3
published: '2026-06-23'
updated: '2026-09-23'
sourceUpdated: '2026-09-23T18:36:50+00:00'
source: CSAF
sourceUrl: 'https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-45135.json'
references:
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-45135.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-45135'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2491896'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-45135'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-45135'
  - url: >-
      https://github.com/caddyserver/caddy/security/advisories/GHSA-m675-2p33-xv9g
  - url: 'https://github.com/php/frankenphp/security/advisories/GHSA-3g8v-8r37-cgjm'
  - url: 'https://github.com/php/frankenphp/security/advisories/GHSA-g966-83w7-6w38'
  - url: 'https://github.com/caddyserver/caddy'
tags:
  - csaf
  - vex
  - red-hat
  - osv
  - go
epss: 0.00676
epssPercentile: 0.50074
aliases:
  - GHSA-m675-2p33-xv9g
ecosystem: go
ingestedAt: '2026-07-20T19:04:14.882Z'
---

## Overview

A flaw was found in Caddy. This vulnerability stems from unsafe handling of Unicode characters within the FastCGI component, specifically when processing request paths containing non-ASCII bytes. An attacker capable of placing content into files served via FastCGI can exploit this by crafting a malicious URL. This can mislead Caddy into executing non-script files as scripts, potentially leading to remote code execution.

## Vendor advisories

- **Red Hat VEX** · Important · updated 2026-09-23 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-45135.json)

**caddy: github.com/caddyserver/caddy/v2: Caddy: Remote Code Execution via Unsafe Unicode Handling in FastCGI** — rated Important by Red Hat. Released 2026-06-23, updated 2026-09-23.

Not affected:

- Red Hat Hardened Images

## Remediation

Refer to the advisory for fix availability.

## Package advisory (CVE-2026-45135)

Affected packages:

- `github.com/caddyserver/caddy/v2 >= 2.7.0, < 2.11.3`

Patched in:

- `github.com/caddyserver/caddy/v2 2.11.3`

Source: https://osv.dev/vulnerability/GHSA-m675-2p33-xv9g