Is this vulnerability remotely exploitable?

Yes, if an attacker can cause the application to parse XML they control or influence, they can remotely trigger excessive entity expansion and degrade service availability.

What level of access does an attacker need?

The attacker only needs the ability to submit XML content to a code path that uses fast-xml-parser with entity expansion enabled—typically via a public or internal API, integration endpoint, or message channel that accepts XML.

What is the safest general fix pattern?

The most robust pattern is to disable XML DTD/entity processing for untrusted input and enforce strict limits on XML size and complexity. Where entities are necessary, they should be tightly constrained and combined with timeouts and resource limits around parsing.

Severity:

HIGH RISK

(7.5)

XML External Entity Expansion (CWE-776) in fast-xml-parser

CVE-2026-26278

Published:

Feb 19, 2026

Status:

Analyzed

Summary

Affected Context

Exploit Preconditions

Why This Happens

Potential Impact

General Mitigation Guidance

How Teams Detect Issues Like This

Frequently Asked Questions

Source

NDV

Recent Vulnerabilities

CWE-77;CWE-78

HIGH RISK

HIGH

(7.3)

OS Command Injection (CWE-78) in Totolink A7100RU setGameSpeedCfg CGI Handler

Remote Code Execution on the Router

April 6, 2026

CWE-77;CWE-78

HIGH RISK

HIGH

(7.3)

OS Command Injection (CWE-78) in Totolink A7100RU setFirewallType Handler

Remote Code Execution on Router Firmware

April 6, 2026

Vulnerability Type

Category:

XML Entity Expansion / Denial of Service

CWE:

CWE-776

Impact:

Denial of Service via resource exhaustion

Severity:

HIGH RISK

(7.5)

CVSS Version:

3.1

Vulnerability Type

Category:

XML Entity Expansion / Denial of Service

CWE:

CWE-776

Impact:

Denial of Service via resource exhaustion

Severity:

HIGH RISK

(7.5)

CVSS Version:

3.1

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355 Bryant St. San Francisco, CA 94107, USA

Ask AI for summary of CodeAnt

XML External Entity Expansion (CWE-776) in fast-xml-parser

Summary

Affected Context

Exploit Preconditions

Why This Happens

Potential Impact

General Mitigation Guidance

How Teams Detect Issues Like This

Frequently Asked Questions

Source

Recent Vulnerabilities

HIGH RISK

HIGH

(7.3)

OS Command Injection (CWE-78) in Totolink A7100RU setGameSpeedCfg CGI Handler

HIGH RISK

HIGH

(7.3)

OS Command Injection (CWE-78) in Totolink A7100RU setFirewallType Handler

Vulnerability Type

Vulnerability Type

Vulnerability Type

Catch This CVE While Code Is Being Written

Ship clean & secure code faster

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