Flysystem: WhitespacePathNormalizer's control-character (CorruptedPathDetected) check is bypassed by malformed UTF-8 in the path, affecting every adapter

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

3.5 · CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N

EPSS

• CVE-2026-102601: 0.34% estimated exploitation activity in the next 30 days; percentile 27.17 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Related public issue (context, not a duplicate) Closed issue #1429 ("Handle non-UTF-8 paths", 2024-03-24) raised exactly this general concern and even suggested detection via pregmatch('//u', $path) !== 1 -- note the reporter's suggested check explicitly compares !== 1, which would correctly treat PCRE's false return as "reject." The maintainer's reply pointed to the PathNormalizer interface as the place to implement this. The control-character check that ended up shipping in WhitespacePathNormalizer (if (pregmatch('#\p{C}+#u', $unixPath))) addresses the general concern but does not use the !== 1-style comparison the original issue suggested -- it uses a bare truthy check, which is exactly the gap this report demonstrates. So this is not a duplicate of #1429; it's a concrete bypass surviving in the fix that issue's concern led to. Vulnerability Details File: src/WhitespacePathNormalizer.php, lines 22-28 (normalizePath()) -- the default PathNormalizer used by Filesystem for every…

Published by the source

29 Sep 2026, 18:10 UTC

Last modified by the source

30 Sep 2026, 21:30 UTC

Source last checked

26 Oct 2026, 14:53 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-cxf4-7mrp-vvpr

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-cxf4-7mrp-vvpr

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# Patch Next advisory brief: CVE-2026-102601

Advisory: Flysystem: WhitespacePathNormalizer's control-character (CorruptedPathDetected) check is bypassed by malformed UTF-8 in the path, affecting every adapter
IDs: CVE-2026-102601, GHSA-cxf4-7mrp-vvpr
Record: https://patchnext.com/advisories/cve-2026-102601 (revision 2, source checked 26 Oct 2026, 14:53 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 3.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: league/flysystem 3.35.3. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist league/flysystem: affected <= 3.35.2; fixed in 3.35.3

## Suggested inspection (read-only)
- Packagist league/flysystem: 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 league/flysystem.
- 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://osv.dev/vulnerability/GHSA-cxf4-7mrp-vvpr (OSV record GHSA-cxf4-7mrp-vvpr lists affected ranges: Packagist league/flysystem >=0 <3.35.3 (fixed))
- Verified: https://github.com/advisories/GHSA-cxf4-7mrp-vvpr (GitHub-reviewed advisory GHSA-cxf4-7mrp-vvpr lists affected ranges: Packagist league/flysystem >=0 <=3.35.2)

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