Flysystem is an open source file storage library for PHP. Prior to 3.35.3, the default WhitespacePathNormalizer in src/WhitespacePathNormalizer.php used by Filesystem across adapters calls preg_match with the u modifier and treats both false and 0 as falsy. A path containing malformed UTF-8 causes PCRE to return false, so paths that also contain control characters bypass CorruptedPathDetected::forPath() in normalizePath(). Filesystem::write() can store such names and Filesystem::listContents() can return the raw ANSI escape sequences, allowing hidden or spoofed terminal file listings when an administrator displays them. This issue is fixed in version 3.35.3.
CVE-2026-102601
LOWPre-NVD 3.53.5—Trending — 3 sources updated this week
EchelonGraph scoreMEDIUM confidence
This low-severity CVE scores 3.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3% (24th percentile of EPSS-scored CVEs). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
Triggered by: NVD CVSS baseline
Sources: epss, secondary
3.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
- Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 3.5Exploit: None knownExposed services: Not assessed
A fix is available — apply it.
- CVSS v3
- 3.5
- EG Score
- 3.5LOWmedium confidence
- EG Risk
- 20EG Risk 20/100CISA SSVC
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity35% × 45%Exploitation0% × 40%Automatability30% × 15%CISA SSVC: Track at low or medium mission impact; Track or Attend at high (mission-essential systems).Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high. - EPSS PROB
- 0.3%
- EPSS %ILE
- 24th
- KEV
- Not listed
CISA SSVCTrack at low or medium mission impact; Track or Attend at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
Exploitation none (no KEV listing, exploit record or EPSS ≥ 50%) · Automatable unknown (not published for this CVE) · Technical impact partial (CVSS below 9.0). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table
Published
September 29, 2026
Last Modified
September 30, 2026
References (4)
- security-advisories@githubhttps://github.com/thephpleague/flysystem/commit/ef4a9a557d769b5d472c403125716706a0d9cc77
- security-advisories@githubhttps://github.com/thephpleague/flysystem/releases/tag/3.35.3
- security-advisories@githubhttps://github.com/thephpleague/flysystem/security/advisories/GHSA-cxf4-7mrp-vvpr
- 134c704f-9b21-4f2e-91b3-4a467353bcc0https://github.com/thephpleague/flysystem/security/advisories/GHSA-cxf4-7mrp-vvpr
Vendor Advisories for CVE-2026-102601(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Affected Packages
(4 across 4 ecosystems)
Debian:12(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| php-league-flysystem | 1.1.10-1, 1.1.10-2, 3.28.0-1, 3.29.1-1, 3.29.1-2 |
| — |
Debian:13(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| php-league-flysystem | 3.29.1-2 |
| — |
Debian:14(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| php-league-flysystem | 3.29.1-2 |
| — |
Packagist(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| league/flysystem | 0.1.0 ... 3.9.0 (256 versions) |
| — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 9× in last 7d / 9× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-10-04 23:21 UTCEPSS rescore
- 2026-10-03 16:38 UTCEG score recompute
- 2026-10-03 14:25 UTCEPSS rescore
- 2026-10-01 19:49 UTCEPSS rescore
- 2026-09-30 19:45 UTCEG score recompute
- 2026-09-30 15:02 UTCEPSS rescore
- 2026-09-29 16:34 UTCEG score recompute
- 2026-09-29 15:38 UTCEG score recompute
- 2026-09-29 15:38 UTCMITRE cvelistV5first tracked
Related CVEs(same product + same CWE)
Frequently asked(5)
What is CVE-2026-102601?
CVE-2026-102601 is a low vulnerability published on September 29, 2026. Flysystem is an open source file storage library for PHP. Prior to 3.35.3, the default WhitespacePathNormalizer in src/WhitespacePathNormalizer.php used by Filesystem across adapters calls preg_match with the u modifier and treats both false and 0 as falsy. A path containing malformed UTF-8 causes…
When was CVE-2026-102601 disclosed?
CVE-2026-102601 was first published on September 29, 2026, with the most recent update on September 30, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-102601 actively exploited?
CVE-2026-102601 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (24th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-102601?
CVE-2026-102601 has a CVSS base score of 3.5 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-102601?
A fix for CVE-2026-102601 is available — its CVE record says: "This issue is fixed in version 3.35.3." The vendor advisories EchelonGraph has for CVE-2026-102601 are linked in the Vendor Advisories panel on this page.
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-102601
Is Your Infrastructure Affected by CVE-2026-102601?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.