FKIE_CVE-2026-31789
Vulnerability from fkie_nvd - Published: 2026-04-07 22:16 - Updated: 2026-07-24 23:10
Severity
9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
5.8 (Medium) - CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:H
5.8 (Medium) - CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:H
Summary
Issue summary: Converting an excessively large OCTET STRING value to
a hexadecimal string leads to a heap buffer overflow on 32 bit platforms.
Impact summary: A heap buffer overflow may lead to a crash or possibly
an attacker controlled code execution or other undefined behavior.
If an attacker can supply a crafted X.509 certificate with an excessively
large OCTET STRING value in extensions such as the Subject Key Identifier
(SKID) or Authority Key Identifier (AKID) which are being converted to hex,
the size of the buffer needed for the result is calculated as multiplication
of the input length by 3. On 32 bit platforms, this multiplication may overflow
resulting in the allocation of a smaller buffer and a heap buffer overflow.
Applications and services that print or log contents of untrusted X.509
certificates are vulnerable to this issue. As the certificates would have
to have sizes of over 1 Gigabyte, printing or logging such certificates
is a fairly unlikely operation and only 32 bit platforms are affected,
this issue was assigned Low severity.
The FIPS modules in 3.6, 3.5, 3.4, 3.3 and 3.0 are not affected by this
issue, as the affected code is outside the OpenSSL FIPS module boundary.
References
{
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "OpenSSL",
"vendor": "OpenSSL",
"versions": [
{
"lessThan": "3.6.2",
"status": "affected",
"version": "3.6.0",
"versionType": "semver"
},
{
"lessThan": "3.5.6",
"status": "affected",
"version": "3.5.0",
"versionType": "semver"
},
{
"lessThan": "3.4.5",
"status": "affected",
"version": "3.4.0",
"versionType": "semver"
},
{
"lessThan": "3.3.7",
"status": "affected",
"version": "3.3.0",
"versionType": "semver"
},
{
"lessThan": "3.0.20",
"status": "affected",
"version": "3.0.0",
"versionType": "semver"
}
]
}
],
"source": "openssl-security@openssl.org"
},
{
"affectedData": [
{
"defaultStatus": "unknown",
"product": "SIMATIC CN 4100",
"vendor": "Siemens",
"versions": [
{
"lessThan": "V5.0",
"status": "affected",
"version": "0",
"versionType": "custom"
}
]
}
],
"source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"
}
],
"configurations": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*",
"matchCriteriaId": "B28A8143-89A4-4332-A1F8-A65FB5AA829F",
"versionEndExcluding": "3.0.20",
"versionStartIncluding": "3.0.0",
"vulnerable": true
},
{
"criteria": "cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*",
"matchCriteriaId": "CF303B21-D9BF-461D-B7B0-A3FE1D557A9F",
"versionEndExcluding": "3.3.7",
"versionStartIncluding": "3.3.0",
"vulnerable": true
},
{
"criteria": "cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*",
"matchCriteriaId": "DCCE43D0-8F17-475D-9EE6-842F758A9905",
"versionEndExcluding": "3.4.5",
"versionStartIncluding": "3.4.0",
"vulnerable": true
},
{
"criteria": "cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*",
"matchCriteriaId": "F6BC0271-444D-4597-BF05-DC60034EAA49",
"versionEndExcluding": "3.5.6",
"versionStartIncluding": "3.5.0",
"vulnerable": true
},
{
"criteria": "cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*",
"matchCriteriaId": "4A9E621D-29D8-418A-BF37-BED333C14507",
"versionEndExcluding": "3.6.2",
"versionStartIncluding": "3.6.0",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "Issue summary: Converting an excessively large OCTET STRING value to\na hexadecimal string leads to a heap buffer overflow on 32 bit platforms.\n\nImpact summary: A heap buffer overflow may lead to a crash or possibly\nan attacker controlled code execution or other undefined behavior.\n\nIf an attacker can supply a crafted X.509 certificate with an excessively\nlarge OCTET STRING value in extensions such as the Subject Key Identifier\n(SKID) or Authority Key Identifier (AKID) which are being converted to hex,\nthe size of the buffer needed for the result is calculated as multiplication\nof the input length by 3. On 32 bit platforms, this multiplication may overflow\nresulting in the allocation of a smaller buffer and a heap buffer overflow.\n\nApplications and services that print or log contents of untrusted X.509\ncertificates are vulnerable to this issue. As the certificates would have\nto have sizes of over 1 Gigabyte, printing or logging such certificates\nis a fairly unlikely operation and only 32 bit platforms are affected,\nthis issue was assigned Low severity.\n\nThe FIPS modules in 3.6, 3.5, 3.4, 3.3 and 3.0 are not affected by this\nissue, as the affected code is outside the OpenSSL FIPS module boundary."
},
{
"lang": "es",
"value": "Resumen del problema: La conversi\u00f3n de un valor OCTET STRING excesivamente grande a una cadena hexadecimal conduce a un desbordamiento de b\u00fafer de mont\u00f3n en plataformas de 32 bits.\n\nResumen del impacto: Un desbordamiento de b\u00fafer de mont\u00f3n puede conducir a un fallo o posiblemente a una ejecuci\u00f3n de c\u00f3digo controlada por un atacante u otro comportamiento indefinido.\n\nSi un atacante puede proporcionar un certificado X.509 manipulado con un valor OCTET STRING excesivamente grande en extensiones como el Identificador de Clave de Sujeto (SKID) o el Identificador de Clave de Autoridad (AKID) que se est\u00e1n convirtiendo a hexadecimal, el tama\u00f1o del b\u00fafer necesario para el resultado se calcula como la multiplicaci\u00f3n de la longitud de entrada por 3. En plataformas de 32 bits, esta multiplicaci\u00f3n puede desbordarse, lo que resulta en la asignaci\u00f3n de un b\u00fafer m\u00e1s peque\u00f1o y un desbordamiento de b\u00fafer de mont\u00f3n.\n\nLas aplicaciones y servicios que imprimen o registran contenidos de certificados X.509 no confiables son vulnerables a este problema. Dado que los certificados tendr\u00edan que tener tama\u00f1os de m\u00e1s de 1 Gigabyte, imprimir o registrar dichos certificados es una operaci\u00f3n bastante improbable y solo las plataformas de 32 bits se ven afectadas, a este problema se le asign\u00f3 una severidad Baja.\n\nLos m\u00f3dulos FIPS en 3.6, 3.5, 3.4, 3.3 y 3.0 no se ven afectados por este problema, ya que el c\u00f3digo afectado est\u00e1 fuera del l\u00edmite del m\u00f3dulo FIPS de OpenSSL."
}
],
"id": "CVE-2026-31789",
"lastModified": "2026-07-24T23:10:00.563",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 9.8,
"baseSeverity": "CRITICAL",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"exploitabilityScore": 3.9,
"impactScore": 5.9,
"source": "nvd@nist.gov",
"type": "Primary"
},
{
"cvssData": {
"attackComplexity": "HIGH",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 5.8,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "LOW",
"integrityImpact": "LOW",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "REQUIRED",
"vectorString": "CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:H",
"version": "3.1"
},
"exploitabilityScore": 1.0,
"impactScore": 4.7,
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"type": "Secondary"
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-31789",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
},
{
"technicalImpact": "total"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-04-09T03:56:05.246752Z",
"version": "2.0.3"
}
}
]
},
"published": "2026-04-07T22:16:21.617",
"references": [
{
"source": "openssl-security@openssl.org",
"tags": [
"Patch"
],
"url": "https://github.com/openssl/openssl/commit/364f095b80601db632b0def6a33316967f863bde"
},
{
"source": "openssl-security@openssl.org",
"tags": [
"Patch"
],
"url": "https://github.com/openssl/openssl/commit/7a9087efd769f362ad9c0e30c7baaa6bbfa65ecf"
},
{
"source": "openssl-security@openssl.org",
"tags": [
"Patch"
],
"url": "https://github.com/openssl/openssl/commit/945b935ac66cc7f1a41f1b849c7c25adb5351f49"
},
{
"source": "openssl-security@openssl.org",
"tags": [
"Patch"
],
"url": "https://github.com/openssl/openssl/commit/a24216018e1ede8ff01a4ff5afff7dfbd443e2f9"
},
{
"source": "openssl-security@openssl.org",
"tags": [
"Patch"
],
"url": "https://github.com/openssl/openssl/commit/a91e537d16d74050dbde50bb0dfb1fe9930f0521"
},
{
"source": "openssl-security@openssl.org",
"tags": [
"Vendor Advisory"
],
"url": "https://openssl-library.org/news/secadv/20260407.txt"
},
{
"source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e",
"url": "https://cert-portal.siemens.com/productcert/html/ssa-032379.html"
}
],
"sourceIdentifier": "openssl-security@openssl.org",
"vulnStatus": "Modified",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-787"
}
],
"source": "openssl-security@openssl.org",
"type": "Secondary"
}
]
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- 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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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
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
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.
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.
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