Is This vulnerability exploited in the wild?

No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.

How severe is This vulnerability?

Medium severity, with a CVSS score of 5.3, published 25 August 2026.

Is there a fix for This vulnerability?

A patch was published on 2026: Fix available in Nokogiri 1.19.3 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is This vulnerability attacked?

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

Check whether you run nokogiri (RubyGems) 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.

Nokogiri XSLT transform memory leak

Severity: medium · CVSS 5.3 · Published 2026-08-25

Nokogiri is a popular XML and HTML parser library used in Ruby applications. A memory leak in its XSLT transform feature allows attackers to send specially crafted input containing null bytes, which causes small heap allocations to leak. For long-running web applications or services that process untrusted data through XSLT transforms, sustained attacks could exhaust available memory and cause service outages.

Technologies: nokogiri (RubyGems). Vendors: RubyGems.

Quick answers

Is This vulnerability exploited in the wild?: No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.
How severe is This vulnerability?: Medium severity, with a CVSS score of 5.3, published 25 August 2026.
Which products and versions are affected?: nokogiri (RubyGems) < 1.19.3.
Is there a fix for This vulnerability?: A patch was published on 2026: Fix available in Nokogiri 1.19.3 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is This vulnerability attacked?: It is attacked over the network, in a software library.
Am I affected?: Check whether you run nokogiri (RubyGems) 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

This vulnerability is a memory leak (CWE-401) in Nokogiri::XSLT::Stylesheet#transform when handling Ruby strings containing null bytes passed as transformation parameters. The root cause is insufficient memory tracking and release during string parameter processing. The attack vector is network-based with no authentication required; an attacker can pass malicious input directly to XSLT transform parameters. Each leaked allocation is approximately 24–32 bytes, so meaningful memory exhaustion requires sustained, high-rate attacker-controlled traffic. The vulnerability does not cause memory corruption or information disclosure, only availability impact through gradual memory consumption. The fix is available in Nokogiri version 1.19.3 and later. Applications can also mitigate by validating untrusted input before passing it to transform parameters.

Affected products

Nokogiri Nokogiri < 1.19.3

Timeline

2026-04-27: disclosed: Original advisory GHSA-v2fc-qm4h-8hqv published
2026-08-25: advisory: Duplicate advisory GHSA-rh9x-7xjc-vwx2 published to NVD and GitHub Advisory Database
2026: patched: Fix available in Nokogiri 1.19.3

References

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