GHSA-V2FC-QM4H-8HQV
Vulnerability from github – Published: 2026-05-06 18:27 – Updated: 2026-09-02 14:42Summary
Nokogiri's Nokogiri::XSLT::Stylesheet#transform leaks a small heap allocation when passed a Ruby string parameter containing a null byte.
For applications that pass attacker-controlled input through XSLT.transform parameters, this may be a vector for a denial of service attack against long-running processes.
Mitigation
Upgrade to Nokogiri >= 1.19.3.
Users may also be able to mitigate this issue without upgrading by validating untrusted transform parameters before passing them to Nokogiri::XSLT::Stylesheet#transform.
Severity
The Nokogiri maintainers have evaluated this as Moderate Severity, CVSS 5.3.
Each leaked allocation is approximately 24–32 bytes, so meaningful memory growth requires sustained attacker-controlled traffic at high call rates. The bug does not cause memory corruption, information disclosure, or any change in the behavior of the transform itself, and the string-handling exception is raised as expected.
Applications that do not pass raw attacker-controlled bytes to XSLT parameters are unlikely to be affected in practice.
Resources
Credit
This vulnerability was responsibly reported by @Captainjack-kor.
{
"affected": [
{
"package": {
"ecosystem": "RubyGems",
"name": "nokogiri"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "1.19.3"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-79771"
],
"database_specific": {
"cwe_ids": [
"CWE-401"
],
"github_reviewed": true,
"github_reviewed_at": "2026-05-06T18:27:38Z",
"nvd_published_at": null,
"severity": "MODERATE"
},
"details": "## Summary\n\nNokogiri\u0027s `Nokogiri::XSLT::Stylesheet#transform` leaks a small heap allocation when passed a Ruby string parameter containing a null byte.\n\nFor applications that pass attacker-controlled input through `XSLT.transform` parameters, this may be a vector for a denial of service attack against long-running processes.\n\n\n## Mitigation\n\nUpgrade to Nokogiri `\u003e= 1.19.3`.\n\nUsers may also be able to mitigate this issue without upgrading by validating untrusted transform parameters before passing them to `Nokogiri::XSLT::Stylesheet#transform`.\n\n\n## Severity\n\nThe Nokogiri maintainers have evaluated this as **Moderate Severity**, CVSS 5.3.\n\nEach leaked allocation is approximately 24\u201332 bytes, so meaningful memory growth requires sustained attacker-controlled traffic at high call rates. The bug does not cause memory corruption, information disclosure, or any change in the behavior of the transform itself, and the string-handling exception is raised as expected.\n\nApplications that do not pass raw attacker-controlled bytes to XSLT parameters are unlikely to be affected in practice.\n\n\n## Resources\n\n- [CWE-401: Missing Release of Memory after Effective Lifetime](https://cwe.mitre.org/data/definitions/401.html)\n\n\n## Credit\n\nThis vulnerability was responsibly reported by @Captainjack-kor.",
"id": "GHSA-v2fc-qm4h-8hqv",
"modified": "2026-09-02T14:42:59Z",
"published": "2026-05-06T18:27:38Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/sparklemotion/nokogiri/security/advisories/GHSA-v2fc-qm4h-8hqv"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-79771"
},
{
"type": "PACKAGE",
"url": "https://github.com/sparklemotion/nokogiri"
},
{
"type": "WEB",
"url": "https://www.vulncheck.com/advisories/nokogiri-before-memory-leak-via-xslt-transform"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
"type": "CVSS_V3"
}
],
"summary": "Nokogiri XSLT transform has a memory leak"
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
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- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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