How severe is CVE-2020-7776?

CVE-2020-7776 has a CVSS score of 6.4/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2020-7776?

CVE-2020-7776 affects the following packages: phpoffice/phpspreadsheet (Packagist), phpoffice/phpexcel (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2020-7776?

Update phpoffice/phpspreadsheet to 1.16.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-7776 is resolved across your whole dependency graph.

How do I detect CVE-2020-7776 in my Packagist dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for phpoffice/phpspreadsheet, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2020-7776 if there is no patch (or I can't update yet)?

Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Is CVE-2020-7776 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2020-7776, including 1 in-the-wild exploitation observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2020-7776?

CVE-2020-7776 has an EPSS (Exploit Prediction Scoring System) score of 1.3%, placing it in the 70th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2020-7776?

CVE-2020-7776 is classified as Cross-site Scripting (XSS) (CWE-79). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2020-7776 published, and has it been updated?

CVE-2020-7776 was published on December 9, 2020 and was last updated on August 7, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐘

🐘 Packagist

Not in CISA KEV

MEDIUM severity

CVE-2020-7776 — phpspreadsheet

MEDIUMFix: PHPOffice/PhpSpreadsheet@0ed5b80

CVE-2020-7776 is a medium-severity (CVSS 6.4) Cross-site Scripting (XSS) vulnerability in phpoffice/phpspreadsheet. 1 public exploit reference exists, so weaponization risk is real. A fix is available for phpoffice/phpspreadsheet — see the affected versions and patch details below.

Cross-site scripting in phpoffice/phpspreadsheet

Also known asGHSA-4mqv-gcr3-pff9SNYK-PHP-PHPOFFICEPHPSPREADSHEET-1048856

Published

Dec 9, 2020

Updated

Aug 7, 2026

Affected

2 pkgs

Patched

1 / 2

Exploits

1 known

Exploitation data as of Oct 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.3%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs70th percentile — riskier than 70% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2020-7776 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

2 pkgs affected

🐘phpoffice/phpspreadsheet🐘phpoffice/phpexcel

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.

Description

This affects the package phpoffice/phpspreadsheet from 0.0.0. The library is vulnerable to XSS when creating an html output from an excel file by adding a comment on any cell. The root cause of this issue is within the HTML writer where user comments are concatenated as part of link and this is returned as HTML. A fix for this issue is available on commit 0ed5b800be2136bcb8fa9c1bdf59abc957a98845/master branch.

Affected Packages

2 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`phpoffice/phpspreadsheet`	all versions	1.16.0`composer require phpoffice/phpspreadsheet:^1.16.0`
🐘Packagist	`phpoffice/phpexcel`	all versions	No fix

Affected Products

1 product · 1 configurations

Application

phpspreadsheetphpoffice

< 1.16.0

range

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

This affects the package phpoffice/phpspreadsheet from 0.0.0. The librar…

snyk.ioNVDJan 2021

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for phpoffice/phpspreadsheet, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update phpoffice/phpspreadsheet to 1.16.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-7776 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

O3 Security · Impact-Aware SCA

Is CVE-2020-7776 in your dependencies?

Find it across Packagist, including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

6.4/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Raw vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N

CWE Classification

CWE-79Cross-site Scripting (XSS)

Weaponization

No known public exploit tooling found.

OpenSSF Scorecard

Package health score

PhpSpreadsheet

6.5/10

Maintained10/10

Code-Review6/10

Branch-ProtectionN/A

Assessed Oct 5, 2026

Timeline

Disclosed

Dec 9, 2020

First exploit

Jan 19, 2021

Last updated

Aug 7, 2026

Identifiers

CVE-2020-7776

GHSA-4mqv-gcr3-pff9

SNYK-PHP-PHPOFFICEPHPSPREADSHEET-1048856

References

Advisorynvd.nist.gov Fixgithub.com Webgithub.com Webgithub.com Webgithub.com Evidencesnyk.io

Related vulnerabilities

This CVE is medium severity; 8 of 8 other CVEs affecting phpoffice/phpspreadsheet are rated as high or higher (top: critical).

CVE-2026-59932CVE-2026-59931CVE-2026-59933CVE-2026-45034CVE-2026-40902CVE-2026-40863CVE-2026-34084CVE-2026-35453

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedAug 7, 2026