FKIE_CVE-2026-80521
Vulnerability from fkie_nvd - Published: 2026-08-26 15:17 - Updated: 2026-09-21 14:17
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved:
af_unix: Unlink scc_entry in unix_del_edge().
Kyle Zeng reported that GC could free a dead SCC partially.
The scenario is as follows:
1) Create two SCCs:
X -. A <-> B
^--'
2) Run the following concurrently:
2-1) send() sk-B to sk-B from sk-X
2-2) close() both A and B
At 2-1), there is a small window where unix_add_edges()
publishes a new edge (B <-> B) to GC but its skb is not queued
by skb_queue_tail().
If 2-2) completes before skb_queue_tail() and GC is triggered,
it judges A <-> B as dead, but B is not freed because GC cannot
collect the not-yet-queued skb holding the B <-> B edge.
X -. A <-> B -. This edge is visible
^--' ^..' but skb is not
This itself is not a problem since the next GC run will judge
B as dead as well and free it finally.
X -. A <.> B -.
^--' ^--'
However, X's SCC forces the next GC to call unix_walk_scc_fast(),
and it iterates over A through B's scc_entry.
Let's unlink scc_entry before freeing the vertex in unix_del_edge().
References
Impacted products
| Vendor | Product | Version |
|---|
{
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/unix/garbage.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "1293fd69a50d188a5788b08ba3741a3e86be1608",
"status": "affected",
"version": "4090fa373f0e763c43610853d2774b5979915959",
"versionType": "git"
},
{
"lessThan": "fe198b077864feafd4aa4b33b1a5ce26f50195a2",
"status": "affected",
"version": "4090fa373f0e763c43610853d2774b5979915959",
"versionType": "git"
},
{
"lessThan": "e3702470ced94fad74d71e2232f022d2eb752a6d",
"status": "affected",
"version": "4090fa373f0e763c43610853d2774b5979915959",
"versionType": "git"
},
{
"lessThan": "594d905195024b228c962627ae5ae7c17bd582a4",
"status": "affected",
"version": "4090fa373f0e763c43610853d2774b5979915959",
"versionType": "git"
},
{
"status": "affected",
"version": "5dfd283f4651d04dbb70ceb9ae5c4a30eda3c52a",
"versionType": "git"
},
{
"status": "affected",
"version": "de7921631ff323369aa63a4324695ab54ea4047e",
"versionType": "git"
},
{
"lessThan": "6.2",
"status": "affected",
"version": "6.1.141",
"versionType": "semver"
},
{
"lessThan": "6.7",
"status": "affected",
"version": "6.6.93",
"versionType": "semver"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"net/unix/garbage.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "6.10"
},
{
"lessThan": "6.10",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.111",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.53",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.10",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\naf_unix: Unlink scc_entry in unix_del_edge().\n\nKyle Zeng reported that GC could free a dead SCC partially.\n\nThe scenario is as follows:\n\n 1) Create two SCCs:\n\n X -. A \u003c-\u003e B\n ^--\u0027\n\n 2) Run the following concurrently:\n\n 2-1) send() sk-B to sk-B from sk-X\n 2-2) close() both A and B\n\nAt 2-1), there is a small window where unix_add_edges()\npublishes a new edge (B \u003c-\u003e B) to GC but its skb is not queued\nby skb_queue_tail().\n\nIf 2-2) completes before skb_queue_tail() and GC is triggered,\nit judges A \u003c-\u003e B as dead, but B is not freed because GC cannot\ncollect the not-yet-queued skb holding the B \u003c-\u003e B edge.\n\n X -. A \u003c-\u003e B -. This edge is visible\n ^--\u0027 ^..\u0027 but skb is not\n\nThis itself is not a problem since the next GC run will judge\nB as dead as well and free it finally.\n\n X -. A \u003c.\u003e B -.\n ^--\u0027 ^--\u0027\n\nHowever, X\u0027s SCC forces the next GC to call unix_walk_scc_fast(),\nand it iterates over A through B\u0027s scc_entry.\n\nLet\u0027s unlink scc_entry before freeing the vertex in unix_del_edge()."
}
],
"id": "CVE-2026-80521",
"lastModified": "2026-09-21T14:17:20.193",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 7.8,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"exploitabilityScore": 1.8,
"impactScore": 5.9,
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary"
}
]
},
"published": "2026-08-26T15:17:05.677",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/1293fd69a50d188a5788b08ba3741a3e86be1608"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/594d905195024b228c962627ae5ae7c17bd582a4"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/e3702470ced94fad74d71e2232f022d2eb752a6d"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/fe198b077864feafd4aa4b33b1a5ce26f50195a2"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Received"
}
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Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
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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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