CVE-2026-34084: PhpSpreadsheet is a library for reading and writing spreadsheet files

This week

CRITICAL 9.8REMOTEUPGRADE

CVE-2026-34084 is a critical-severity flaw (CVSS 9.8) affecting phpspreadsheet. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

PhpSpreadsheet is a library for reading and writing spreadsheet files. In versions 1.30.2 and earlier, 2.0.0 through 2.1.14, 2.2.0 through 2.4.3, 3.3.0 through 3.10.3, and 4.0.0 through 5.5.0, when the filename argument to IOFactory::load() is user-controlled, an attacker can supply a PHP stream wrapper path (such as phar://, ftp://, or ssh2.sftp://) that passes the is_file() check in File::assertFile(). The phar:// wrapper triggers deserializati

Why this priority

Critical severity
Public exploit reference
CISA SSVC: automatable with total technical impact
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.7% (top 47%)
CISA exploited list	No
Weakness	CWE-502, CWE-918
Published	2026-05-05
Last modified	2026-07-24

Publisher (CNA): GitHub, Inc. · Vendor: phpoffice

Last updated 2026-07-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-05 20:16 UTCPublished CVE record published
2026-07-24 22:10 UTCUpdated Record last modified

phpoffice phpspreadsheet UPGRADE

Affected: < 1.30.3 · >= 2.0.0 and < 2.1.15 · >= 2.2.0 and < 2.4.4 · >= 3.3.0 and < 3.10.4 · >= 4.0.0 and < 5.6.0

Fixed in: 1.30.3, 2.1.15, 2.4.4, 3.10.4, 5.6.0

Safe to downgrade to: a release before 2.0.0

1. Check installed version

apt-cache policy phpspreadsheet || rpm -q phpspreadsheet || phpspreadsheet --version

2. UPGRADE to 1.30.3 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade phpspreadsheet

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade phpspreadsheet

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 2.0.0 (Debian / Ubuntu)

apt-cache madison phpspreadsheet sudo apt install phpspreadsheet=<VERSION_BEFORE_2.0.0> sudo apt-mark hold phpspreadsheet

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list phpspreadsheet sudo dnf downgrade phpspreadsheet-<VERSION_BEFORE_2.0.0> sudo dnf versionlock add phpspreadsheet

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Exact fixes by distribution

Composer (PHP) · phpoffice/phpspreadsheet · FIXED · 5.6.0 · vulnerable: >= 4.0.0, <= 5.5.0 · source

composer require "phpoffice/phpspreadsheet:>=5.6.0"

Fedora 46 · fzssh · FIXED · 1.4.0-2.fc46 · FEDORA-2026-8004fcd067 · source

sudo dnf upgrade --advisory=FEDORA-2026-8004fcd067

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Write-up: github.com/PHPOffice/PhpSpreadsheet/security/advisories/GHSA-q4q6-r8wh-5cgh

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-34084?

phpspreadsheet: upgrade to 1.30.3, 2.1.15, 2.4.4, 3.10.4, 5.6.0. Exact commands for each OS are on this page.

Is CVE-2026-34084 being exploited?

CVE-2026-34084 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-34084 affect?

CVE-2026-34084 affects phpspreadsheet. Severity is critical (CVSS 9.8). PhpSpreadsheet is a library for reading and writing spreadsheet files. In versions 1.30.2 and earlier, 2.0.0 through 2.1.14, 2.2.0 through 2.4.3, 3.3.0 through 3.10.3, and 4.0.0 through 5.5.0, when the filename argument to IOFactory::load()

How urgent is CVE-2026-34084?

Priority 61/100. Critical severity; Public exploit reference; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action

Software pages

PHP vulnerabilities

Related CVEs

CVE-2026-40296 MEDIUM 5.4 UPGRADE PhpSpreadsheet is a pure PHP library for reading and writing spreadsheet files
CVE-2026-40863 HIGH 7.5 UPGRADE PhpSpreadsheet is a pure PHP library for reading and writing spreadsheet files
CVE-2026-40902 HIGH 7.5 UPGRADE PhpSpreadsheet is a pure PHP library for reading and writing spreadsheet files
CVE-2026-35453 MEDIUM 5.4 UPGRADE PhpSpreadsheet is a library for reading and writing spreadsheet files

References

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