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High, CVSS 8.9

FrankenPHP's unicode case-folding length expansion causes incorrect split_path index (SCRIPT_NAME/PATH_INFO confusion) in FrankenPHP

CVE-2026-24895GHSA-g966-83w7-6w38

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (github.com/dunglas/frankenphp 1.11.2), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
8.9 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X · score source
EPSS
  • CVE-2026-24895: 0.65% estimated exploitation activity in the next 30 days; percentile 51.23 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary FrankenPHP’s CGI path splitting logic improperly handles Unicode characters during case conversion. The logic computes the split index (for finding .php) on a lowercased copy of the request path but applies that byte index to the original path. Because strings.ToLower() in Go can increase the byte length of certain UTF-8 characters (e.g., Ⱥ expands when lowercased), the computed index may not align with the correct position in the original string. This results in an incorrect SCRIPTNAME and SCRIPTFILENAME, potentially causing FrankenPHP to execute a file other than the one intended by the URI. Details The vulnerability resides in the splitPos() function and its usage within splitCgiPath(). The logic attempts to find the script extension (e.g., .php) in a case-insensitive manner by lowercasing the path: The issue is that the returned idx represents a byte offset within lowerPath. However, splitCgiPath() uses this index to slice the original path: This logic relies on the…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 1 · created ·

    Published from ghsa record GHSA-g966-83w7-6w38

Agent brief

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# Patch Next advisory brief: CVE-2026-24895

Advisory: FrankenPHP's unicode case-folding length expansion causes incorrect split_path index (SCRIPT_NAME/PATH_INFO confusion) in FrankenPHP
IDs: CVE-2026-24895, GHSA-g966-83w7-6w38
Record: https://patchnext.com/advisories/cve-2026-24895 (revision 1, source checked 26 Oct 2026, 15:18 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/dunglas/frankenphp 1.11.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/dunglas/frankenphp: affected < 1.11.2; fixed in 1.11.2

## Suggested inspection (read-only)
- Go github.com/dunglas/frankenphp: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/dunglas/frankenphp.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-g966-83w7-6w38 (GitHub-reviewed advisory GHSA-g966-83w7-6w38 lists affected ranges: Go github.com/dunglas/frankenphp >=0 <1.11.2)

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