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CVE-2026-57437

Nokogiri: Possible Use-After-Free when directly using `NokogirI::XML::XPathContext` beyond document lifetime

1.7 LowFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
Low

Exploit likelihood

0.40%Up 0.1 points since Jun 26, 2026
90%50%10%1%

What each source reports

CVE List Score used 1.7

Nokogiri: Possible Use-After-Free when directly using `NokogirI::XML::XPathContext` beyond document lifetime

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.

Record
CVE-2026-57437
CVSS 4.0
1.7 LowCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/U:Clear
Weakness
CWE-416
Updated
2026-11-02
EUVDEUVD-2026-39428 1.7

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.

Record
EUVD-2026-39428
CVSS 4.0
1.7 LowCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/U:Clear
Updated
2026-11-02
GitHub AdvisoriesGHSA-p67v-3w7g-wjg7 1.7

Nokogiri: Possible Use-After-Free when directly using `NokogirI::XML::XPathContext` beyond document lifetime

Summary

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.

Nokogiri 1.19.4 makes XPathContext keep its source document alive for as long as the context exists.

Only the CRuby implementation is affected. JRuby is not affected.

Severity

The 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.

Mitigation

Upgrade to Nokogiri 1.19.4 or later.

As 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.

Credit

This issue was responsibly reported by Zheng Yu from depthfirst.com.

Record
GHSA-p67v-3w7g-wjg7
CVSS 4.0
1.7 LowCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/U:Clear
Weakness
CWE-416
Updated
2026-11-02
NVD 1.7

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.

Record
CVE-2026-57437
CVSS 4.0
1.7 LowCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Clear
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Weakness
CWE-416
Updated
2026-11-02
OSVBELL-CVE-2026-57437 5.3
Record
BELL-CVE-2026-57437
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Updated
2026-11-02
OSV 1.7

Nokogiri: Possible Use-After-Free when directly using `NokogirI::XML::XPathContext` beyond document lifetime

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.

Record
CVE-2026-57437
CVSS 4.0
1.7 LowCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/U:Clear
Weakness
CWE-416
Updated
2026-11-02
Show 4 moreShow less
OSVDEBIAN-CVE-2026-57437 5.3

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.

Record
DEBIAN-CVE-2026-57437
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Updated
2026-11-02
OSVGHSA-p67v-3w7g-wjg7 1.7

Nokogiri: Possible Use-After-Free when directly using `NokogirI::XML::XPathContext` beyond document lifetime

Summary

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.

Nokogiri 1.19.4 makes XPathContext keep its source document alive for as long as the context exists.

Only the CRuby implementation is affected. JRuby is not affected.

Severity

The 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.

Mitigation

Upgrade to Nokogiri 1.19.4 or later.

As 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.

Credit

This issue was responsibly reported by Zheng Yu from depthfirst.com.

Record
GHSA-p67v-3w7g-wjg7
CVSS 4.0
1.7 LowCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/U:Clear
Weakness
CWE-416
Updated
2026-11-02
OSVUBUNTU-CVE-2026-57437 1.7

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.

Record
UBUNTU-CVE-2026-57437
CVSS 4.0
1.7 LowCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/U:Clear
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Updated
2026-11-02
OSVAZL-91071 No score

CVE-2026-57437 affecting package rubygem-nokogiri for versions less than 1.19.4-1

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.

Record
AZL-91071
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
nokogiri
RubyGems
 before 1.19.4
1.19.4
rubygem-nokogiri
Azure Linux:3
 before 1.19.4-1
1.19.4-1
ruby-nokogiri
Alpaquita:stream
 1.13.9-r1 up to 1.19.4-r0
1.19.4-r0
ruby-nokogiri
Debian:12
 All versions, plus listed versions
1.13.10+dfsg-21.14.2+dfsg-11.14.3+dfsg-11.14.3+dfsg-21.15.4+dfsg-1
Show 12 moreShow less
1.16.0+dfsg-11.16.0+dfsg-21.16.2+dfsg-11.16.4+dfsg-11.17.2+dfsg-1~exp11.18.10+dfsg-11.18.10+dfsg-21.18.10+dfsg-31.18.2+dfsg-11.19.1+dfsg-11.19.3+dfsg-11.19.4+dfsg-1
 None known
ruby-nokogiri
Debian:13
 All versions, plus listed versions
1.18.10+dfsg-11.18.10+dfsg-21.18.10+dfsg-31.18.2+dfsg-11.19.1+dfsg-11.19.3+dfsg-11.19.4+dfsg-1
 None known
ruby-nokogiri
Debian:14
 before 1.19.4+dfsg-1, plus listed versions
1.18.10+dfsg-11.18.10+dfsg-21.18.10+dfsg-31.18.2+dfsg-11.19.1+dfsg-11.19.3+dfsg-1
1.19.4+dfsg-1
nokogiri
RubyGems
 before 1.19.4, plus listed versions
1.0.01.0.11.0.21.0.31.0.4
Show 45 moreShow less
1.0.51.0.61.0.71.1.01.1.11.10.01.10.0.rc11.10.11.10.101.10.21.10.31.10.41.10.51.10.61.10.71.10.81.10.91.11.01.11.0.rc11.11.0.rc21.11.0.rc31.11.0.rc41.11.11.11.21.11.31.11.41.11.51.11.61.11.71.12.01.12.0.rc11.12.11.12.21.12.31.12.41.12.51.13.01.13.11.13.101.13.21.13.31.13.41.13.51.13.61.13.7
1.19.4
ruby-nokogiri
Ubuntu:Pro:14.04:LTS
 All versions, plus listed versions
1.5.9-21.5.9-31.6.0-11.6.1+ds-11.6.1+ds-1ubuntu0.1~esm1
 None known
ruby-nokogiri
Ubuntu:16.04:LTS
 All versions, plus listed versions
1.6.6.2+ds-2build21.6.6.3-11.6.7-11.6.7.1-11.6.7.2-31.6.7.2-3build11.6.7.2-3ubuntu0.1
 None known
ruby-nokogiri
Ubuntu:18.04:LTS
 All versions, plus listed versions
1.8.0-11.8.1-11.8.1-1build11.8.2-1build11.8.2-1ubuntu0.1
 None known
Show 6 moreShow less
Affected packages
PackageAffectedFixed
ruby-nokogiri
Ubuntu:Pro:20.04:LTS
 All versions, plus listed versions
1.10.3+dfsg1-21.10.4+dfsg1-11.10.7+dfsg1-11.10.7+dfsg1-21.10.7+dfsg1-2build11.10.7+dfsg1-2ubuntu0.1~esm2
 None known
ruby-nokogiri
Ubuntu:Pro:22.04:LTS
 All versions, plus listed versions
1.11.1+dfsg-2ubuntu11.11.7+dfsg-31.11.7+dfsg-3build11.13.1+dfsg-21.13.1+dfsg-2ubuntu0.1~esm1
 None known
ruby-nokogiri
Ubuntu:24.04:LTS
 All versions, plus listed versions
1.14.3+dfsg-21.16.2+dfsg-11.16.2+dfsg-1build1
 None known
ruby-nokogiri
Ubuntu:25.10
 All versions, plus listed versions
1.16.4+dfsg-1build11.18.2+dfsg-1build1
 None known
ruby-nokogiri
Ubuntu:26.10
 All versions, plus listed versions
1.18.10+dfsg-31.19.1+dfsg-11.19.3+dfsg-11.19.4+dfsg-1
 None known
ruby-nokogiri
Ubuntu:26.04:LTS
 All versions, plus listed versions
1.18.2+dfsg-1build11.18.10+dfsg-21.18.10+dfsg-3
 None known

History

History
RecordedChangedSources
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-57437 is a low vulnerability (CVSS 1.7) in Nokogiri, published June 19, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.40%, the 34th percentile. Fixed in nokogiri 1.19.4.

References

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Left out here: 144 versions. The JSON record has them.

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