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CVE-2026-35453· NVD / CVE Program· CNA GitHub_M

PhpSpreadsheet XSS via number format text substitution in HTML Writer

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.

MediumCVSS 4.8 · v4.0—No exploit Fix available
Published
May 5, 2026
Updated
Jul 24, 2026
EPSS
0.2% · 13th percentile
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Report tools

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Action score

19

Monitor

Low priority for now.

CVSS
19 / 40 · 4.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

CISA SSVC decision

Exploitation
proof of concept
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · GitHub_M
4.8
NVD has not scored this yet; the score shown is the CNA’s.

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Noroxi analysis

No Noroxi analysis for this record yet

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Affected systems

VendorProduct
phpofficephpspreadsheet

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • phpoffice phpspreadsheetbefore 1.30.4
  • phpoffice phpspreadsheet2.0.0 and later · before 2.1.16
  • phpoffice phpspreadsheet2.2.0 and later · before 2.4.5
  • phpoffice phpspreadsheet3.3.0 and later · before 3.10.5
  • phpoffice phpspreadsheet4.0.0 and later · before 5.7.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • PHPOffice PhpSpreadsheet

    • >= 4.0.0, <= 5.6.0, >= 3.3.0, <= 3.10.4, >= 2.2.0, <= 2.4.4, >= 2.0.0, <= 2.1.15, <= 1.30.3affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Packagistphpoffice/phpspreadsheetfrom 2.0.0 · before 2.1.162.1.16
Packagistphpoffice/phpspreadsheetfrom 2.2.0 · before 2.4.52.4.5
Packagistphpoffice/phpspreadsheetfrom 3.3.0 · before 3.10.53.10.5
Packagistphpoffice/phpspreadsheetfrom 4.0.0 · before 5.7.05.7.0
Packagistphpoffice/phpspreadsheetbefore 1.30.41.30.4

Same product

phpoffice: all records

Other highest-scoring records for the same primary product.

  • CVE-2018-19277securityScan() in PHPOffice PhpSpreadsheet through 1.5.0 allows a bypass of protection mechanisms for XXE via UTF-7 encoding in a .xlsx file
    37Monitor
  • CVE-2026-45034PhpSpreadsheet: File::prohibitWrappers bypass
    36Monitor
  • CVE-2026-34084PhpSpreadsheet SSRF and RCE via PHP stream wrappers in IOFactory::load
    36Monitor
  • CVE-2024-45291Path traversal and Server-Side Request Forgery in HTML writer when embedding images is enabled in PHPSpreadsheet
    35Monitor
  • CVE-2019-12331PHPOffice PhpSpreadsheet before 1.8.0 has an XXE issue.
    35Monitor
  • CVE-2025-54370PhpSpreadsheet vulnerable to SSRF when reading and displaying a processed HTML document in the browser
    34Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Packagist:phpoffice/phpspreadsheet1.30.4Package registry (OSV)
Packagist:phpoffice/phpspreadsheet2.1.16Package registry (OSV)
Packagist:phpoffice/phpspreadsheet2.4.5Package registry (OSV)
Packagist:phpoffice/phpspreadsheet3.10.5Package registry (OSV)
Packagist:phpoffice/phpspreadsheet5.7.0Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2024-56365487 days apartPhpSpreadsheet vulnerable to unauthorized reflected XSS in the constructor of the Downloader class
    33Monitor
  • CVE-2024-56366487 days apartPhpSpreadsheet vulnerable to unauthorized reflected XSS in the Accounting.php file
    33Monitor
  • CVE-2024-56408487 days apartPhpSpreadsheet allows unauthorized reflected XSS in `Convert-Online.php` file
    33Monitor
  • CVE-2024-56409487 days apartPhpSpreadsheet vulnerable to unauthorized reflected XSS in Currency.php file
    33Monitor
  • CVE-2026-402961 days apartPhpSpreadsheet vulnerable to XSS in HTML writer via custom number format codes
    21Monitor
  • CVE-2025-22131470 days apartCross-Site Scripting (XSS) vulnerability in generateNavigation() function
    20Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • A low-privileged account is enough.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
Integrity
Availability
Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
A
Scope
X

Weakness class (CWE)

CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

nvd-secondary

Root cause

User content is inserted into the page as HTML. The browser interprets the content as code rather than data.

The bug in code

The whole CWE-79 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

ts
commentEl.innerHTML = comment.body;

Fixed

ts
commentEl.textContent = comment.body;

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

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