{"id":"CVE-2026-57437","aliases":["GHSA-p67v-3w7g-wjg7"],"url":"https://o3.security/vulnerability/CVE-2026-57437","summary":"Nokogiri: Possible Use-After-Free when directly using `NokogirI::XML::XPathContext` beyond document lifetime","details":"### Summary\n\n`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.\n\nThis 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.\n\nNokogiri 1.19.4 makes `XPathContext` keep its source document alive for as long as the context exists.\n\nOnly the CRuby implementation is affected. JRuby is not affected.\n\n### Severity\n\nThe Nokogiri maintainers have evaluated this as low severity. Reaching it requires an unusual API-usage pattern that does not arise during normal use. The application must construct an `XML::XPathContext` directly and continue using it after allowing its source document to be garbage-collected. Nokogiri 1.19.4 makes this pattern safe with no change to the public API. The context now keeps its source document alive for as long as it exists.\n\n### Mitigation\n\nUpgrade to Nokogiri 1.19.4 or later.\n\nAs a workaround, ensure the source document remains referenced for as long as any `XPathContext` created from it is in use. The standard `Document#xpath`, `#css`, and related search methods already do this and are unaffected.\n\n### Credit\n\nThis issue was responsibly reported by Zheng Yu from depthfirst.com.","published":"2026-06-25T14:34:09.482Z","modified":"2026-10-21T02:58:44.661664298Z","cvss":null,"epss":{"score":0.00402,"percentile":0.34088,"asOf":"2026-09-17"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"RubyGems","name":"nokogiri","fixedVersion":"1.19.4"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/57xxx/CVE-2026-57437.json"},{"type":"ADVISORY","url":"https://github.com/sparklemotion/nokogiri/security/advisories/GHSA-p67v-3w7g-wjg7"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-57437"},{"type":"PACKAGE","url":"https://github.com/sparklemotion/nokogiri"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-21T02:58:44.661664298Z"}}