CVE-2026-57437 Nokogiri: Possible Use-After-Free when directly using `NokogirI::XML::XPathContext` beyond document lifetime
Developers using Nokogiri's XPathContext directly may experience crashes if the underlying document is garbage collected before the context is used.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-57437?
CVE-2026-57437 is a low-severity use after free vulnerability in sparklemotion nokogiri, published on 25 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Nokogiri is an open source XML and HTML library for the Ruby programming language. Prior to 1.19.4, Nokogiri::XML::XPathContext did not keep its source document alive for garbage collection. If an XPathContext outlived its document and the document was collected, evaluating an XPath expression could read invalid memory and potentially segfault. This is only reachable when application code constructs an XPathContext directly and lets the document become unreachable while continuing to use the context. The normal Document#xpath, #css, and related search methods are not affected, and it is not triggerable by malicious document input. This vulnerability is fixed in 1.19.4.
Weakness: CWE-416
Which versions are affected by CVE-2026-57437?
2 open source packages ship an affected version, including nokogiri. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
nokogiri RubyGems | All versions | 1.19.4 |
nokogiri RubyGems | All versions | 1.19.4 |
Products include Nokogiri Nokogiri.
How do I fix CVE-2026-57437?
Upgrade nokogiri to 1.19.4 or later.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-57437 being exploited?
There is no known exploitation of CVE-2026-57437 in the wild and no public exploit code.
Other vulnerabilities in sparklemotion nokogiri
- CVE-2026-79770 Nokogiri before 1.19.3 ReDoS via CSS selector tokenizer
- CVE-2022-23476 Unchecked return value from xmlTextReaderExpand in Nokogiri
- CVE-2021-41098 Improper Restriction of XML External Entity Reference (XXE) in Nokogiri on JRuby
- CVE-2012-6685 Nokogiri is vulnerable to XML External Entity (XXE) attack
- CVE-2026-79771 Nokogiri before 1.19.3 Memory Leak via XSLT Transform
Sources
Also known as AZL-91071, BELL-CVE-2026-57437, CLEANSTART-2026-VA15262, DEBIAN-CVE-2026-57437, GHSA-p67v-3w7g-wjg7, MINI-78h9-g9x6-6f2x and 8 more.