What is CVE-2026-45071?

CVE-2026-45071 is a low-severity XML external entity injection (XXE) vulnerability in symfony/dom-crawler (composer), affecting versions < 5.4.52. It is fixed in 5.4.52, 6.4.40, 7.4.12, 8.0.12. An XML parser processes external entity references in untrusted input, causing the server to fetch internal resources or remote URLs.

Which packages are affected by CVE-2026-45071?

symfony/dom-crawler (composer) versions < 5.4.52; symfony/symfony (composer) versions < 5.4.52.

Is there a fix for CVE-2026-45071?

Yes. CVE-2026-45071 is fixed in 5.4.52, 6.4.40, 7.4.12, 8.0.12. Upgrade to this version or later.

Is CVE-2026-45071 exploitable, and should I be worried?

Whether CVE-2026-45071 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk.

What actually determines whether CVE-2026-45071 is exploitable, and how bad it is?

Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.

CVE-2026-45071 in symfony/dom-crawler

Q: Which packages are affected by CVE-2026-45071?

symfony/dom-crawler (composer) versions < 5.4.52; symfony/symfony (composer) versions < 5.4.52.

Q: Is there a fix for CVE-2026-45071?

Yes. CVE-2026-45071 is fixed in 5.4.52, 6.4.40, 7.4.12, 8.0.12. Upgrade to this version or later.

Q: Is CVE-2026-45071 exploitable, and should I be worried?

Whether CVE-2026-45071 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk.

Q: What actually determines whether CVE-2026-45071 is exploitable, and how bad it is?

Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.

Q: How do I fix CVE-2026-45071?

Upgrade: symfony/dom-crawler to 5.4.52 or later, symfony/symfony to 5.4.52 or later, symfony/dom-crawler to 6.4.40 or later, symfony/dom-crawler to 7.4.12 or later, symfony/dom-crawler to 8.0.12 or later, symfony/symfony to 6.4.40 or later, symfony/symfony to 7.4.12 or later, symfony/symfony to 8.0.12 or later.

Summary

Symfony has XXE (Local File Disclosure) in DomCrawler::addXmlContent() via validateOnParse = true

Description

symfony/dom-crawler provides the Crawler class for navigating HTML/XML documents with CSS/XPath selectors; symfony/browser-kit's HttpBrowser uses it to parse fetched pages.

Crawler::addXmlContent() sets DOMDocument::$validateOnParse = true before calling loadXML(). Setting validateOnParse re-enables libxml's DTD subset processing, including external entity resolution, even though LIBXML_NONET is passed. LIBXML_NONET blocks network fetches but not file:// entities. An attacker-supplied XML document with a SYSTEM "file:///etc/passwd" entity is therefore expanded.

Resolution

The Crawler::addXmlContent method does not set the validateOnParse flag anymore.

The patch for this issue is available here for branch 5.4.

Credits

Symfony would like to thank Claude Mythos Preview (via Project Glasswing) for reporting the issue and providing the fix.

Impact

An XML parser processes external entity references in untrusted input, causing the server to fetch internal resources or remote URLs. Typical impact: local file disclosure, server-side request forgery, or denial of service.

Affected versions

symfony/dom-crawler (< 5.4.52) symfony/symfony (< 5.4.52) symfony/dom-crawler (>= 6.0.0, < 6.4.40) symfony/dom-crawler (>= 7.0.0, < 7.4.12) symfony/dom-crawler (>= 8.0.0, < 8.0.12) symfony/symfony (>= 6.0.0, < 6.4.40) symfony/symfony (>= 7.0.0, < 7.4.12) symfony/symfony (>= 8.0.0, < 8.0.12)

Security releases

symfony/dom-crawler → 5.4.52 (composer) symfony/symfony → 5.4.52 (composer) symfony/dom-crawler → 6.4.40 (composer) symfony/dom-crawler → 7.4.12 (composer) symfony/dom-crawler → 8.0.12 (composer) symfony/symfony → 6.4.40 (composer) symfony/symfony → 7.4.12 (composer) symfony/symfony → 8.0.12 (composer)

Kodem intelligence

Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.

Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.

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Remediation advice

Upgrade the following packages to resolve this vulnerability:

symfony/dom-crawler to 5.4.52 or later; symfony/symfony to 5.4.52 or later; symfony/dom-crawler to 6.4.40 or later; symfony/dom-crawler to 7.4.12 or later; symfony/dom-crawler to 8.0.12 or later; symfony/symfony to 6.4.40 or later; symfony/symfony to 7.4.12 or later; symfony/symfony to 8.0.12 or later

Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.

Frequently Asked Questions

What is CVE-2026-45071? CVE-2026-45071 is a low-severity XML external entity injection (XXE) vulnerability in symfony/dom-crawler (composer), affecting versions < 5.4.52. It is fixed in 5.4.52, 6.4.40, 7.4.12, 8.0.12. An XML parser processes external entity references in untrusted input, causing the server to fetch internal resources or remote URLs.
Which packages are affected by CVE-2026-45071?
- symfony/dom-crawler (composer) (versions < 5.4.52)
- symfony/symfony (composer) (versions < 5.4.52)
Is there a fix for CVE-2026-45071? Yes. CVE-2026-45071 is fixed in 5.4.52, 6.4.40, 7.4.12, 8.0.12. Upgrade to this version or later.
Is CVE-2026-45071 exploitable, and should I be worried? Whether CVE-2026-45071 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
What actually determines whether CVE-2026-45071 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
How do I fix CVE-2026-45071?
- Upgrade symfony/dom-crawler to 5.4.52 or later
- Upgrade symfony/symfony to 5.4.52 or later
- Upgrade symfony/dom-crawler to 6.4.40 or later
- Upgrade symfony/dom-crawler to 7.4.12 or later
- Upgrade symfony/dom-crawler to 8.0.12 or later
- Upgrade symfony/symfony to 6.4.40 or later
- Upgrade symfony/symfony to 7.4.12 or later
- Upgrade symfony/symfony to 8.0.12 or later