CVE-2026-35453

What it is

PhpSpreadsheet is a library for reading and writing spreadsheet files. In versions 1.30.3 and earlier, 2.0.0 through 2.1.15, 2.2.0 through 2.4.4, 3.3.0 through 3.10.4, and 4.0.0 through 5.6.0, the HTML Writer skips htmlspecialchars() output escaping when a cell uses a custom number format containing the @ text placeholder with additional literal text (e.g., @ "items"). The escaping is only applied when the formatted output strictly equals the original cell value. When the format code contains @ with quoted literal text, the formatter substitutes the raw cell value into the format string and returns early without invoking the escaping callback. An attacker who can control cell content in a spreadsheet processed by the HTML Writer can inject arbitrary HTML and JavaScript into the generated output. This issue has been fixed in versions 1.30.4, 2.1.16, 2.4.5, 3.10.5, and 5.7.0.

At a glance

Exploitability

Can be exploited over the network with a low-privilege account, but needs a user to act. Limited direct impact.

Exploit odds

0.2% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-05-05 20:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-07-24 21:10 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.2% in the next 30 days (EPSS).
• Severity: 4.8 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-05-05 20:16 UTC

Last modified

2026-07-24 21:10 UTC

Exploit probability

0.2% · EPSS, next 30 days

Weakness

CWE-79 · Cross-site scripting

Record status

Analyzed

Affected

• Phpoffice Phpspreadsheet < 1.30.4
• Phpoffice Phpspreadsheet < 2.1.16
• Phpoffice Phpspreadsheet < 2.4.5
• Phpoffice Phpspreadsheet < 3.10.5
• Phpoffice Phpspreadsheet < 5.7.0

Attack profile CVSS 4.0 · 4.8

Attack vector

Network

Complexity

Low

Attack requirements

None

Privileges needed

Low

User interaction

Active

Confidentiality

None

Integrity

None

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-35453.md and follow it. Check whether this project is affected by CVE-2026-35453. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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