FKIE_CVE-2026-56389
Vulnerability from fkie_nvd - Published: 2026-07-29 11:16 - Updated: 2026-10-23 23:10
Severity
Summary
GNU Bison allows for an execution of an arbitrary program during HTML report generation due to improper handling of grammar-defined configuration variables. A grammar file can override the executable used for the XML‑to‑HTML transformation step via %define tool.xsltproc, which is accepted without restriction and passed directly to execvp().
When running bison --html on a attacker-provided grammar, this behavior allows execution of an arbitrary program with the privileges of the Bison process.
Maintainers of this project were notified about this vulnerability, and fixed the issue in commit 3169c1e7a2c6acc4c59dfcf8b089896d6881925b. However, they did not provide vulnerable version range. Version 3.8.2 was tested and confirmed as vulnerable, other versions were not tested but might also be vulnerable.
References
{
"affected": [
{
"affectedData": [
{
"defaultStatus": "unknown",
"product": "Bison",
"repo": "https://cgit.git.savannah.gnu.org/cgit/bison.git/",
"vendor": "GNU",
"versions": [
{
"status": "affected",
"version": "3.8.2",
"versionType": "semver"
}
]
}
],
"source": "cvd@cert.pl"
}
],
"configurations": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:gnu:bison:3.8.2:*:*:*:*:*:*:*",
"matchCriteriaId": "524B249F-965A-4AA8-9F93-54298A0F69FB",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "GNU Bison allows for an execution of an arbitrary program during HTML report generation due to improper handling of grammar-defined configuration variables. A grammar file can override the executable used for the XML\u2011to\u2011HTML transformation step via %define tool.xsltproc, which is accepted without restriction and passed directly to execvp().\n \nWhen running bison --html on a attacker-provided grammar, this behavior allows execution of an arbitrary program with the privileges of the Bison process.\n\n\nMaintainers of this project were notified about this vulnerability, and fixed the issue in commit 3169c1e7a2c6acc4c59dfcf8b089896d6881925b. However, they did not provide vulnerable version range. Version 3.8.2 was tested\u00a0and confirmed as vulnerable, other versions were not tested but might also be vulnerable."
},
{
"lang": "es",
"value": "GNU Bison permite la ejecuci\u00f3n de un programa arbitrario durante la generaci\u00f3n de informes HTML debido a un manejo inadecuado de las variables de configuraci\u00f3n definidas por la gram\u00e1tica. Un archivo de gram\u00e1tica puede anular el ejecutable utilizado para el paso de transformaci\u00f3n de XML a HTML a trav\u00e9s de %define tool.xsltproc, que se acepta sin restricciones y se pasa directamente a execvp().\n\nAl ejecutar bison --html en una gram\u00e1tica proporcionada por un atacante, este comportamiento permite la ejecuci\u00f3n de un programa arbitrario con los privilegios del proceso de Bison.\n\nLos mantenedores de este proyecto fueron notificados sobre esta vulnerabilidad y corrigieron el problema en el commit 3169c1e7a2c6acc4c59dfcf8b089896d6881925b. Sin embargo, no proporcionaron el rango de versiones vulnerables. La versi\u00f3n 3.8.2 fue probada y confirmada como vulnerable; otras versiones no fueron probadas, pero tambi\u00e9n podr\u00edan ser vulnerables."
}
],
"id": "CVE-2026-56389",
"lastModified": "2026-10-23T23:10:00.157",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 8.6,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "NONE",
"scope": "CHANGED",
"userInteraction": "REQUIRED",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H",
"version": "3.1"
},
"exploitabilityScore": 1.8,
"impactScore": 6.0,
"source": "nvd@nist.gov",
"type": "Primary"
}
],
"cvssMetricV40": [
{
"cvssData": {
"Automatable": "NOT_DEFINED",
"Recovery": "NOT_DEFINED",
"Safety": "NOT_DEFINED",
"attackComplexity": "LOW",
"attackRequirements": "NONE",
"attackVector": "LOCAL",
"availabilityRequirement": "NOT_DEFINED",
"baseScore": 6.8,
"baseSeverity": "MEDIUM",
"confidentialityRequirement": "NOT_DEFINED",
"exploitMaturity": "NOT_DEFINED",
"integrityRequirement": "NOT_DEFINED",
"modifiedAttackComplexity": "NOT_DEFINED",
"modifiedAttackRequirements": "NOT_DEFINED",
"modifiedAttackVector": "NOT_DEFINED",
"modifiedPrivilegesRequired": "NOT_DEFINED",
"modifiedSubAvailabilityImpact": "NOT_DEFINED",
"modifiedSubConfidentialityImpact": "NOT_DEFINED",
"modifiedSubIntegrityImpact": "NOT_DEFINED",
"modifiedUserInteraction": "NOT_DEFINED",
"modifiedVulnAvailabilityImpact": "NOT_DEFINED",
"modifiedVulnConfidentialityImpact": "NOT_DEFINED",
"modifiedVulnIntegrityImpact": "NOT_DEFINED",
"privilegesRequired": "NONE",
"providerUrgency": "NOT_DEFINED",
"subAvailabilityImpact": "LOW",
"subConfidentialityImpact": "LOW",
"subIntegrityImpact": "LOW",
"userInteraction": "ACTIVE",
"valueDensity": "NOT_DEFINED",
"vectorString": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:H/VA:L/SC:L/SI:L/SA:L/E:X/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:X",
"version": "4.0",
"vulnAvailabilityImpact": "LOW",
"vulnConfidentialityImpact": "NONE",
"vulnIntegrityImpact": "HIGH",
"vulnerabilityResponseEffort": "NOT_DEFINED"
},
"source": "cvd@cert.pl",
"type": "Secondary"
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-56389",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
},
{
"technicalImpact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-07-29T12:20:29.904189Z",
"version": "2.0.3"
}
}
]
},
"published": "2026-07-29T11:16:49.767",
"references": [
{
"source": "cvd@cert.pl",
"tags": [
"Third Party Advisory"
],
"url": "https://cert.pl/en/posts/2026/07/CVE-2026-56389"
},
{
"source": "cvd@cert.pl",
"tags": [
"Product"
],
"url": "https://cgit.git.savannah.gnu.org/cgit/bison.git/"
},
{
"source": "cvd@cert.pl",
"tags": [
"Patch"
],
"url": "https://cgit.git.savannah.gnu.org/cgit/bison.git/commit/?id=3169c1e7a2c6acc4c59dfcf8b089896d6881925b"
}
],
"sourceIdentifier": "cvd@cert.pl",
"vulnStatus": "Analyzed",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-78"
}
],
"source": "cvd@cert.pl",
"type": "Secondary"
}
]
}
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Sightings
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Nomenclature
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Vulnerability timeline
Sightings and recorded dates, grouped by day · UTC
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
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The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.