---
title: "CVE-2026-45034: PHPSpreadsheet has a patch bypass for CVE-2026-34084"
url: https://erroneo.us/security/cve/CVE-2026-45034/
description: "CVE-2026-45034 (phpoffice/phpspreadsheet (Composer (PHP))): PhpSpreadsheet is a pure PHP library for reading and writing spreadsheet files. Prior to 1.30.5…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-06-22
date_modified: 2026-06-23
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-45034"
kev: false
cvss: 9.2
epss: 0.00462
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-45034: PHPSpreadsheet has a patch bypass for CVE-2026-34084

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Not in CISA KEV , but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 0.5% , percentile 39: FIRST’s model estimates a 0.5% chance of exploitation activity in the next 30 days, higher than 39% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes phpoffice/phpspreadsheet (Composer (PHP)) <= 1.30.4, fixed in 1.30.5 . Check your lockfile, including transitive dependencies.

## What it is

PhpSpreadsheet is a pure PHP library for reading and writing spreadsheet files. Prior to 1.30.5, CVE-2026-34084 was patched by the helper File::prohibitWrappers. The helper calls parseurl($filename, PHPURLSCHEME) and then checks isstring($scheme) && strlen($scheme) > 1 to reject stream wrappers such as phar://, php://, data:// or expect://. The check is not equivalent to "does the path contain a wrapper". When the input has the form phar:///path/file.phar/inner with three or more slashes after the scheme, parseurl returns boolean false instead of returning the scheme string. The isstring($scheme) branch is therefore skipped, the helper returns without throwing, and the caller proceeds. PHP's stream layer, however, still treats phar:///... as a valid phar wrapper and opens the underlying phar file. The result is that IOFactory::load($attackerPath) walks past the patch and still touches the phar wrapper. On PHP 7.x, simply reaching the phar wrapper via isfile is enough for PHP to automatically deserialize the phar metadata, which in turn invokes the magic methods wakeup and destruct of an attacker controlled object and gives full RCE. On PHP 8.x, automatic metadata deserialization for plain file ops was removed, so the chain at the PhpSpreadsheet layer reduces to a phar wrapper file read primitive, and RCE only resurfaces if the downstream consumer ever calls Phar::getMetadata. This vulnerability is fixed in 1.30.5.

## Affected packages

- Composer (PHP) `phpoffice/phpspreadsheet` <= 1.30.4 → fixed: 1.30.5

## Affected products (CVE record)

- PHPOffice PhpSpreadsheet: < 1.30.5

## Severity

- GitHub_M CVSS 4.0: 9.2 `CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`
- GitHub CVSS 4.0: 9.2 `CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.46% probability of exploitation activity in the next 30 days; percentile 39.

## Sources

- [GitHub Advisory GHSA-87m4-826x-3crx](https://github.com/advisories/GHSA-87m4-826x-3crx)
- [CVE.org record CVE-2026-45034](https://www.cve.org/CVERecord?id=CVE-2026-45034)
- [NVD entry CVE-2026-45034](https://nvd.nist.gov/vuln/detail/CVE-2026-45034)
- [github.com](https://github.com/PHPOffice/PhpSpreadsheet/security/advisories/GHSA-87m4-826x-3crx)
- [github.com](https://github.com/advisories/GHSA-q4q6-r8wh-5cgh)

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Source page: https://erroneo.us/security/cve/CVE-2026-45034/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt