CVE-2026-56391 (GCVE-0-2026-56391)
Vulnerability from cvelistv5 – Published: 2026-07-24 07:44 – Updated: 2026-07-24 12:31 X_Open Source
VLAI
EPSS
VEX
Title
Out‑of‑bounds Read in GNU coreutils
Summary
GNU coreutils uniq is vulnerable to an out‑of‑bounds read due to incorrect handling of multibyte input when the -w (--check-chars) option is used. The find_field() function miscalculates the byte length of characters by repeatedly processing a fixed pointer instead of advancing through the input, resulting in an inflated length value.
This incorrect length is later used in a memcmp operation, causing reads beyond the allocated buffer when processing crafted multibyte input.
When running GNU coreutils uniq with attacker-provided arguments, this behavior leads to a crash and potential adjacent heap memory exposure.
This issue has been fixed in the commit d64e35a8a4c0e4608321433e0d84d917e4e36371.
Severity
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-07-24 12:31 UTC
CWE
- CWE-125 - Out-of-bounds Read
Assigner
References
3 references
| URL | Tags |
|---|---|
| https://cert.pl/en/posts/2026/07/CVE-2026-56391 | third-party-advisory |
| https://git.savannah.gnu.org/cgit/coreutils.git/ | product |
| https://git.savannah.gnu.org/cgit/coreutils.git/c… | patch |
Impacted products
{
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-56391",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "no"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-07-24T12:31:16.655541Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-07-24T12:31:34.245Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"modules": [
"uniq"
],
"product": "coreutils",
"vendor": "GNU",
"versions": [
{
"lessThanOrEqual": "9.11",
"status": "affected",
"version": "9.5",
"versionType": "custom"
}
]
}
],
"credits": [
{
"lang": "en",
"type": "finder",
"value": "Micha\u0142 Majchrowicz (AFINE Team)"
},
{
"lang": "en",
"type": "finder",
"value": "Marcin Wyczechowski (AFINE Team)"
}
],
"descriptions": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "GNU coreutils \u003ci\u003euniq\u003c/i\u003e is vulnerable to an out\u2011of\u2011bounds read due to incorrect handling of multibyte input when the \u003ci\u003e-w (--check-chars)\u003c/i\u003e option is used. The \u003ci\u003efind_field()\u003c/i\u003e function miscalculates the byte length of characters by repeatedly processing a fixed pointer instead of advancing through the input, resulting in an inflated length value. \u003cbr\u003eThis incorrect length is later used in a memcmp operation, causing reads beyond the allocated buffer when processing crafted multibyte input.\u003cbr\u003e\u003cbr\u003eWhen running GNU coreutils \u003ci\u003euniq\u003c/i\u003e with attacker-provided arguments, this behavior leads to a crash and potential adjacent heap memory exposure.\u003cbr\u003e\u003cp\u003eThis issue has been fixed in the commit d64e35a8a4c0e4608321433e0d84d917e4e36371.\u003c/p\u003e"
}
],
"value": "GNU coreutils uniq is vulnerable to an out\u2011of\u2011bounds read due to incorrect handling of multibyte input when the -w (--check-chars) option is used. The find_field() function miscalculates the byte length of characters by repeatedly processing a fixed pointer instead of advancing through the input, resulting in an inflated length value. \nThis incorrect length is later used in a memcmp operation, causing reads beyond the allocated buffer when processing crafted multibyte input.\n\nWhen running GNU coreutils uniq with attacker-provided arguments, this behavior leads to a crash and potential adjacent heap memory exposure.\n\n\nThis issue has been fixed in the commit d64e35a8a4c0e4608321433e0d84d917e4e36371."
}
],
"metrics": [
{
"cvssV4_0": {
"Automatable": "NOT_DEFINED",
"Recovery": "NOT_DEFINED",
"Safety": "NOT_DEFINED",
"attackComplexity": "LOW",
"attackRequirements": "NONE",
"attackVector": "LOCAL",
"baseScore": 4.6,
"baseSeverity": "MEDIUM",
"exploitMaturity": "NOT_DEFINED",
"privilegesRequired": "NONE",
"providerUrgency": "NOT_DEFINED",
"subAvailabilityImpact": "NONE",
"subConfidentialityImpact": "NONE",
"subIntegrityImpact": "NONE",
"userInteraction": "ACTIVE",
"valueDensity": "NOT_DEFINED",
"vectorString": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N",
"version": "4.0",
"vulnAvailabilityImpact": "LOW",
"vulnConfidentialityImpact": "LOW",
"vulnIntegrityImpact": "NONE",
"vulnerabilityResponseEffort": "NOT_DEFINED"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en",
"value": "GENERAL"
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-125",
"description": "CWE-125 Out-of-bounds Read",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-07-24T07:44:45.581Z",
"orgId": "4bb8329e-dd38-46c1-aafb-9bf32bcb93c6",
"shortName": "CERT-PL"
},
"references": [
{
"tags": [
"third-party-advisory"
],
"url": "https://cert.pl/en/posts/2026/07/CVE-2026-56391"
},
{
"tags": [
"product"
],
"url": "https://git.savannah.gnu.org/cgit/coreutils.git/"
},
{
"tags": [
"patch"
],
"url": "https://git.savannah.gnu.org/cgit/coreutils.git/commit/?id=d64e35a8a4c0e4608321433e0d84d917e4e36371"
}
],
"source": {
"discovery": "EXTERNAL"
},
"tags": [
"x_open-source"
],
"title": "Out\u2011of\u2011bounds Read in GNU coreutils",
"x_generator": {
"engine": "Vulnogram 0.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "4bb8329e-dd38-46c1-aafb-9bf32bcb93c6",
"assignerShortName": "CERT-PL",
"cveId": "CVE-2026-56391",
"datePublished": "2026-07-24T07:44:45.581Z",
"dateReserved": "2026-06-21T11:40:32.790Z",
"dateUpdated": "2026-07-24T12:31:34.245Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2026-56391",
"date": "2026-11-01",
"epss": "0.00131",
"percentile": "0.02693"
},
"microsoft_vex": {
"current_release_date": "2026-10-22T01:08:19.000Z",
"cve": "CVE-2026-56391",
"id": "msrc_CVE-2026-56391",
"initial_release_date": "2026-08-07T00:22:37.000Z",
"product_status:fixed": "1",
"product_status:known_affected": "1",
"product_status:known_not_affected": "1",
"source": "Microsoft CSAF VEX",
"status": "final",
"title": "Out\u2011of\u2011bounds Read in GNU coreutils",
"url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-56391.json",
"version": "2"
},
"nvd": {
"cve": {
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"modules": [
"uniq"
],
"product": "coreutils",
"vendor": "GNU",
"versions": [
{
"lessThanOrEqual": "9.11",
"status": "affected",
"version": "9.5",
"versionType": "custom"
}
]
}
],
"source": "cvd@cert.pl"
}
],
"configurations": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:gnu:coreutils:*:*:*:*:*:*:*:*",
"matchCriteriaId": "32AA16DF-2A52-4FEA-8A2D-94AEE9EEFD22",
"versionEndIncluding": "9.11",
"versionStartIncluding": "9.5",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "GNU coreutils uniq is vulnerable to an out\u2011of\u2011bounds read due to incorrect handling of multibyte input when the -w (--check-chars) option is used. The find_field() function miscalculates the byte length of characters by repeatedly processing a fixed pointer instead of advancing through the input, resulting in an inflated length value. \nThis incorrect length is later used in a memcmp operation, causing reads beyond the allocated buffer when processing crafted multibyte input.\n\nWhen running GNU coreutils uniq with attacker-provided arguments, this behavior leads to a crash and potential adjacent heap memory exposure.\n\n\nThis issue has been fixed in the commit d64e35a8a4c0e4608321433e0d84d917e4e36371."
},
{
"lang": "es",
"value": "GNU coreutils uniq es vulnerable a una lectura fuera de l\u00edmites debido a un manejo incorrecto de entrada multibyte cuando se utiliza la opci\u00f3n -w (--check-chars). La funci\u00f3n find_field() calcula incorrectamente la longitud en bytes de los caracteres al procesar repetidamente un puntero fijo en lugar de avanzar a trav\u00e9s de la entrada, lo que resulta en un valor de longitud inflado.\nEsta longitud incorrecta se utiliza posteriormente en una operaci\u00f3n memcmp, causando lecturas m\u00e1s all\u00e1 del b\u00fafer asignado al procesar entrada multibyte manipulada.\n\nAl ejecutar GNU coreutils uniq con argumentos proporcionados por el atacante, este comportamiento conduce a un fallo y a una posible exposici\u00f3n de memoria adyacente del heap.\n\nEste problema ha sido corregido en el commit d64e35a8a4c0e4608321433e0d84d917e4e36371."
}
],
"id": "CVE-2026-56391",
"lastModified": "2026-10-24T13:10:00.147",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 6.1,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "LOW",
"integrityImpact": "NONE",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "REQUIRED",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:H",
"version": "3.1"
},
"exploitabilityScore": 1.8,
"impactScore": 4.2,
"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": 4.6,
"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": "NONE",
"subConfidentialityImpact": "NONE",
"subIntegrityImpact": "NONE",
"userInteraction": "ACTIVE",
"valueDensity": "NOT_DEFINED",
"vectorString": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N/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": "LOW",
"vulnIntegrityImpact": "NONE",
"vulnerabilityResponseEffort": "NOT_DEFINED"
},
"source": "cvd@cert.pl",
"type": "Secondary"
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-56391",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
},
{
"technicalImpact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-07-24T12:31:16.655541Z",
"version": "2.0.3"
}
}
]
},
"published": "2026-07-24T09:16:25.003",
"references": [
{
"source": "cvd@cert.pl",
"tags": [
"Third Party Advisory"
],
"url": "https://cert.pl/en/posts/2026/07/CVE-2026-56391"
},
{
"source": "cvd@cert.pl",
"tags": [
"Product"
],
"url": "https://git.savannah.gnu.org/cgit/coreutils.git/"
},
{
"source": "cvd@cert.pl",
"tags": [
"Patch"
],
"url": "https://git.savannah.gnu.org/cgit/coreutils.git/commit/?id=d64e35a8a4c0e4608321433e0d84d917e4e36371"
}
],
"sourceIdentifier": "cvd@cert.pl",
"vulnStatus": "Analyzed",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-125"
}
],
"source": "cvd@cert.pl",
"type": "Secondary"
}
]
}
},
"redhat_vex": {
"aggregate_severity": "Moderate",
"current_release_date": "2026-09-16T10:35:16+00:00",
"cve": "CVE-2026-56391",
"id": "CVE-2026-56391",
"initial_release_date": "2026-07-24T07:44:45.581000+00:00",
"product_status:fixed": "24",
"product_status:known_affected": "14",
"product_status:known_not_affected": "4",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "coreutils: GNU coreutils uniq: Denial of Service and information disclosure via out-of-bounds read with multibyte input",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-56391.json",
"version": "3"
},
"vulnrichment": {
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-56391",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "no"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-07-24T12:31:16.655541Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-07-24T12:31:22.474Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"modules": [
"uniq"
],
"product": "coreutils",
"vendor": "GNU",
"versions": [
{
"lessThanOrEqual": "9.11",
"status": "affected",
"version": "9.5",
"versionType": "custom"
}
]
}
],
"credits": [
{
"lang": "en",
"type": "finder",
"value": "Micha\u0142 Majchrowicz (AFINE Team)"
},
{
"lang": "en",
"type": "finder",
"value": "Marcin Wyczechowski (AFINE Team)"
}
],
"descriptions": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "GNU coreutils \u003ci\u003euniq\u003c/i\u003e is vulnerable to an out\u2011of\u2011bounds read due to incorrect handling of multibyte input when the \u003ci\u003e-w (--check-chars)\u003c/i\u003e option is used. The \u003ci\u003efind_field()\u003c/i\u003e function miscalculates the byte length of characters by repeatedly processing a fixed pointer instead of advancing through the input, resulting in an inflated length value. \u003cbr\u003eThis incorrect length is later used in a memcmp operation, causing reads beyond the allocated buffer when processing crafted multibyte input.\u003cbr\u003e\u003cbr\u003eWhen running GNU coreutils \u003ci\u003euniq\u003c/i\u003e with attacker-provided arguments, this behavior leads to a crash and potential adjacent heap memory exposure.\u003cbr\u003e\u003cp\u003eThis issue has been fixed in the commit d64e35a8a4c0e4608321433e0d84d917e4e36371.\u003c/p\u003e"
}
],
"value": "GNU coreutils uniq is vulnerable to an out\u2011of\u2011bounds read due to incorrect handling of multibyte input when the -w (--check-chars) option is used. The find_field() function miscalculates the byte length of characters by repeatedly processing a fixed pointer instead of advancing through the input, resulting in an inflated length value. \nThis incorrect length is later used in a memcmp operation, causing reads beyond the allocated buffer when processing crafted multibyte input.\n\nWhen running GNU coreutils uniq with attacker-provided arguments, this behavior leads to a crash and potential adjacent heap memory exposure.\n\n\nThis issue has been fixed in the commit d64e35a8a4c0e4608321433e0d84d917e4e36371."
}
],
"metrics": [
{
"cvssV4_0": {
"Automatable": "NOT_DEFINED",
"Recovery": "NOT_DEFINED",
"Safety": "NOT_DEFINED",
"attackComplexity": "LOW",
"attackRequirements": "NONE",
"attackVector": "LOCAL",
"baseScore": 4.6,
"baseSeverity": "MEDIUM",
"exploitMaturity": "NOT_DEFINED",
"privilegesRequired": "NONE",
"providerUrgency": "NOT_DEFINED",
"subAvailabilityImpact": "NONE",
"subConfidentialityImpact": "NONE",
"subIntegrityImpact": "NONE",
"userInteraction": "ACTIVE",
"valueDensity": "NOT_DEFINED",
"vectorString": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N",
"version": "4.0",
"vulnAvailabilityImpact": "LOW",
"vulnConfidentialityImpact": "LOW",
"vulnIntegrityImpact": "NONE",
"vulnerabilityResponseEffort": "NOT_DEFINED"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en",
"value": "GENERAL"
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-125",
"description": "CWE-125 Out-of-bounds Read",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-07-24T07:44:45.581Z",
"orgId": "4bb8329e-dd38-46c1-aafb-9bf32bcb93c6",
"shortName": "CERT-PL"
},
"references": [
{
"tags": [
"third-party-advisory"
],
"url": "https://cert.pl/en/posts/2026/07/CVE-2026-56391"
},
{
"tags": [
"product"
],
"url": "https://git.savannah.gnu.org/cgit/coreutils.git/"
},
{
"tags": [
"patch"
],
"url": "https://git.savannah.gnu.org/cgit/coreutils.git/commit/?id=d64e35a8a4c0e4608321433e0d84d917e4e36371"
}
],
"source": {
"discovery": "EXTERNAL"
},
"tags": [
"x_open-source"
],
"title": "Out\u2011of\u2011bounds Read in GNU coreutils",
"x_generator": {
"engine": "Vulnogram 0.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "4bb8329e-dd38-46c1-aafb-9bf32bcb93c6",
"assignerShortName": "CERT-PL",
"cveId": "CVE-2026-56391",
"datePublished": "2026-07-24T07:44:45.581Z",
"dateReserved": "2026-06-21T11:40:32.790Z",
"dateUpdated": "2026-07-24T12:31:34.245Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
Loading…
Loading…
Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.
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.
Vulnerability timeline
Sightings and recorded dates, grouped by day · UTC
Loading timeline…
Loading…
Loading…
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.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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.
Loading…
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.