UBUNTU-CVE-2026-56123 (CVE-2026-56123)
Vulnerability from osv_ubuntu – Published: 2026-06-25 17:17 – Updated: 2026-07-06 18:42 – Source website
VLAI
Details
socat versions 1.8.0.0 through 1.8.1.1 contain a heap-based buffer overflow vulnerability that allows a malicious SOCKS5 proxy server to overwrite adjacent heap memory by exploiting a sign-extension flaw in the DOMAINNAME reply parser. During connection setup, the domain name length byte is read through a signed char field causing a negative bytes_to_read value that is implicitly converted to size_t, resulting in an unbounded heap write into the 262-byte reply buffer with attacker-controlled size and content.
Severity
8.1 (High)
9.8 (Critical)
N/A (UNKNOWN)
References
| URL | Type | |
|---|---|---|
{
"affected": [
{
"ecosystem_specific": {
"availability": "No subscription required",
"binaries": [
{
"binary_name": "socat",
"binary_version": "1.8.0.0-4ubuntu0.1"
}
]
},
"package": {
"ecosystem": "Ubuntu:24.04:LTS",
"name": "socat",
"purl": "pkg:deb/ubuntu/socat@1.8.0.0-4ubuntu0.1?arch=source\u0026distro=noble"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "1.8.0.0-4ubuntu0.1"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.7.4.4-2",
"1.8.0.0-4",
"1.8.0.0-4build1",
"1.8.0.0-4build2",
"1.8.0.0-4build3"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "socat",
"binary_version": "1.8.0.3-1build1"
}
]
},
"package": {
"ecosystem": "Ubuntu:25.10",
"name": "socat",
"purl": "pkg:deb/ubuntu/socat@1.8.0.3-1build1?arch=source\u0026distro=questing"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.8.0.2-1",
"1.8.0.3-1",
"1.8.0.3-1build1"
]
},
{
"ecosystem_specific": {
"availability": "No subscription required",
"binaries": [
{
"binary_name": "socat",
"binary_version": "1.8.1.1-1ubuntu0.1"
}
]
},
"package": {
"ecosystem": "Ubuntu:26.04:LTS",
"name": "socat",
"purl": "pkg:deb/ubuntu/socat@1.8.1.1-1ubuntu0.1?arch=source\u0026distro=resolute"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "1.8.1.1-1ubuntu0.1"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.8.0.3-1build1",
"1.8.1.0-1",
"1.8.1.0-2",
"1.8.1.1-1"
]
}
],
"aliases": [],
"details": "socat versions 1.8.0.0 through 1.8.1.1 contain a heap-based buffer overflow vulnerability that allows a malicious SOCKS5 proxy server to overwrite adjacent heap memory by exploiting a sign-extension flaw in the DOMAINNAME reply parser. During connection setup, the domain name length byte is read through a signed char field causing a negative bytes_to_read value that is implicitly converted to size_t, resulting in an unbounded heap write into the 262-byte reply buffer with attacker-controlled size and content.",
"id": "UBUNTU-CVE-2026-56123",
"modified": "2026-07-06T18:42:27Z",
"published": "2026-06-25T17:17:00Z",
"references": [
{
"type": "REPORT",
"url": "https://ubuntu.com/security/CVE-2026-56123"
},
{
"type": "REPORT",
"url": "https://www.cve.org/CVERecord?id=CVE-2026-56123"
},
{
"type": "ADVISORY",
"url": "https://ubuntu.com/security/notices/USN-8511-1"
}
],
"related": [
"USN-8511-1"
],
"schema_version": "1.7.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
},
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
},
{
"score": "medium",
"type": "Ubuntu"
}
],
"upstream": [
"CVE-2026-56123"
]
}
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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.
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.
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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.
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