Is CVE-2026-45186 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-45186 being exploited in the wild.

How severe is CVE-2026-45186?

Low severity, with a CVSS score of 2.9, published 10 May 2026.

Which products and versions are affected?

Libexpat Project Expat before 2.8.1.

Is there a fix for CVE-2026-45186?

A patch was published on 2026-05-10: libexpat 2.8.1 released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-45186 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-45186?

Check whether you run Libexpat Project Expat or Libexpat Project Libexpat at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-45186: libexpat denial of service via attribute name collision check

CVE-2026-45186 · Severity: low · CVSS 2.9 · Published 2026-05-10

libexpat is a widely used software library for processing XML data. A vulnerability in how it handles XML attributes allows an attacker to crash or slow down applications by sending a specially crafted, moderately sized XML file. This can lead to a denial of service, impacting the availability of web services and applications that rely on this library for data processing.

Technologies: Libexpat Project Expat, Libexpat Project Libexpat. Vendors: Libexpat Project.

Quick answers

Is CVE-2026-45186 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-45186 being exploited in the wild.
How severe is CVE-2026-45186?: Low severity, with a CVSS score of 2.9, published 10 May 2026.
Which products and versions are affected?: Libexpat Project Expat before 2.8.1.
Is there a fix for CVE-2026-45186?: A patch was published on 2026-05-10: libexpat 2.8.1 released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-45186 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-45186?: Check whether you run Libexpat Project Expat or Libexpat Project Libexpat at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A vulnerability classified as Inefficient Algorithmic Complexity (CWE-407) exists in libexpat's attribute name collision check mechanism. The root cause is quadratic runtime behavior triggered when parsing XML input with a large number of attributes. An unauthenticated remote attacker can exploit this by providing a moderately sized, crafted XML document, leading to excessive CPU consumption and a denial of service (DoS). While some initial reports suggested a low severity, the maintainers and Red Hat have identified the attack vector as network-based with low complexity, resulting in a CVSS score of 7.5. The issue is resolved in libexpat version 2.8.1.

Affected products

libexpat project libexpat before 2.8.1
Red Hat Enterprise Linux 6, 7, 8, 9, 10
Red Hat JBoss Core Services 2.4.62.SP4

Timeline

2026-05-08: other: Fixing pull request submitted to GitHub
2026-05-10: patched: libexpat 2.8.1 released
2026-05-10: disclosed: Vulnerability disclosed and CVE assigned
2026-06-03: advisory: Red Hat issued security advisories for multiple products

References

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