RHSA-2026:40724
Vulnerability from csaf_redhat - Published: 2026-07-16 05:27 - Updated: 2026-09-21 11:51A flaw was found in GNU coreutils, specifically in the `unexpand` utility. This vulnerability, a heap-based buffer overflow, occurs due to an integer overflow when `unexpand` processes unusually large tab stop values provided by a local attacker. This can lead to an undersized memory buffer, allowing subsequent operations to write beyond its boundaries. Successful exploitation can cause the `unexpand` utility to crash, potentially resulting in a denial of service or enabling further memory manipulation.
| Product | Identifier | Version | Remediation |
|---|---|---|---|
| Unresolved product id: Red Hat Hardened Images:coreutils-0:9.11-5.hum1@aarch64 | — |
Vendor Fix
fix
Workaround
|
|
| Unresolved product id: Red Hat Hardened Images:coreutils-0:9.11-5.hum1@src | — |
Vendor Fix
fix
Workaround
|
|
| Unresolved product id: Red Hat Hardened Images:coreutils-0:9.11-5.hum1@x86_64 | — |
Vendor Fix
fix
Workaround
|
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"cve": "CVE-2026-56392",
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"name": "Out-of-bounds Write"
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"discovery_date": "2026-07-24T09:01:08.479352+00:00",
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"notes": [
{
"category": "description",
"text": "A flaw was found in GNU coreutils, specifically in the `unexpand` utility. This vulnerability, a heap-based buffer overflow, occurs due to an integer overflow when `unexpand` processes unusually large tab stop values provided by a local attacker. This can lead to an undersized memory buffer, allowing subsequent operations to write beyond its boundaries. Successful exploitation can cause the `unexpand` utility to crash, potentially resulting in a denial of service or enabling further memory manipulation.",
"title": "Vulnerability description"
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"text": "coreutils: GNU coreutils unexpand: Denial of Service via crafted tab stop values",
"title": "Vulnerability summary"
},
{
"category": "other",
"text": "A Moderate impact heap-based buffer overflow flaw was found in the `unexpand` utility of GNU coreutils. This vulnerability arises from an integer overflow when processing unusually large tab stop values, leading to an undersized buffer. A local attacker could exploit this by providing crafted input, causing the utility to crash and potentially leading to a denial of service or arbitrary memory manipulation.",
"title": "Statement"
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"scores": [
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"attackVector": "LOCAL",
"availabilityImpact": "LOW",
"baseScore": 4.4,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "NONE",
"integrityImpact": "LOW",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "REQUIRED",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:L",
"version": "3.1"
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"threats": [
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}
],
"title": "coreutils: GNU coreutils unexpand: Denial of Service via crafted tab stop values"
}
]
}
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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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.