CVE-2026-57435 Nokogiri: Possible Use-After-Free when setting an attribute value via `Nokogiri::XML::Attr#value=` or `#content=`
An attacker can cause a denial of service via a use-after-free vulnerability in the Nokogiri Ruby library when modifying XML attribute values.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-57435?
CVE-2026-57435 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’s CRuby native extension could leave a Ruby wrapper pointing to freed memory when replacing the value of an XML attribute. If Ruby code had already accessed an attribute child node, Nokogiri::XML::Attr#value= could free the underlying native child node while the wrapper remained reachable through the document node cache. A later use of the freed child node or a Ruby GC mark could dereference an invalid pointer, causing an invalid read and a possible segfault. This vulnerability is fixed in 1.19.4.
Which versions are affected by CVE-2026-57435?
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-2026-57435?
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-2026-57435 being exploited?
There is no known exploitation of CVE-2026-57435 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-91065, BELL-CVE-2026-57435, CLEANSTART-2026-TU47442, DEBIAN-CVE-2026-57435, GHSA-phwj-rprq-35pp, MINI-2w78-pj55-25m5 and 8 more.