CVE-2026-57236
CVE-2026-57236 is a high-severity vulnerability in Nokogiri with a CVSS 3.x base score of 8.2. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-416.
Key facts
- Severity: High (CVSS 3.x base score 8.2)
- CVSS v4: 1.7
- EPSS exploit prediction: 0% (25th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2026-39419
- Weakness: CWE-416
- Affected product: Nokogiri
- Published:
- Last modified:
Description
Nokogiri is an open source XML and HTML library for the Ruby programming language. Prior to 1.19.4, calling Document#encoding= with an invalid encoding (e.g., a non-string, or a string containing a null byte) raises an exception, but only after freeing the document's current encoding string without replacing it. The document is left referencing freed memory, so the next call to Document#encoding reads invalid memory, which can cause a segfault or leak freed bytes into a Ruby String. Affects the CRuby (libxml2) implementation only; JRuby is not affected. This vulnerability is fixed in 1.19.4.
Frequently asked questions
- What is CVE-2026-57236?
- Nokogiri is an open source XML and HTML library for the Ruby programming language. Prior to 1.19.4, calling Document#encoding= with an invalid encoding (e.g., a non-string, or a string containing a null byte) raises an exception, but only after freeing the document's current encoding string without replacing it. The document is left referencing freed memory, so the next call to Document#encoding reads invalid memory, which can cause a segfault or leak freed bytes into a Ruby String. Affects the CRuby (libxml2) implementation only; JRuby is not affected. This vulnerability is fixed in 1.19.4.
- How severe is CVE-2026-57236?
- CVE-2026-57236 has a CVSS 3.x base score of 8.2, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability high.
- Is CVE-2026-57236 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (25th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2026-57236?
- CVE-2026-57236 affects Nokogiri. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2026-57236?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- Does CVE-2026-57236 have an EU (EUVD) identifier?
- Yes. CVE-2026-57236 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-39419.
- When was CVE-2026-57236 published?
- CVE-2026-57236 was published on 2026-06-25 and last updated on 2026-06-26.
References
Affected products (1)
- cpe:2.3:a:nokogiri:nokogiri:*:*:*:*:*:ruby:*:*
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