CVE-2026-31772 (GCVE-0-2026-31772)
Vulnerability from cvelistv5 – Published: 2026-05-01 14:15 – Updated: 2026-08-05 12:25
VLAI
EPSS
VEX
Title
Bluetooth: hci_sync: fix stack buffer overflow in hci_le_big_create_sync
Summary
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: hci_sync: fix stack buffer overflow in hci_le_big_create_sync
hci_le_big_create_sync() uses DEFINE_FLEX to allocate a
struct hci_cp_le_big_create_sync on the stack with room for 0x11 (17)
BIS entries. However, conn->num_bis can hold up to HCI_MAX_ISO_BIS (31)
entries — validated against ISO_MAX_NUM_BIS (0x1f) in the caller
hci_conn_big_create_sync(). When conn->num_bis is between 18 and 31,
the memcpy that copies conn->bis into cp->bis writes up to 14 bytes
past the stack buffer, corrupting adjacent stack memory.
This is trivially reproducible: binding an ISO socket with
bc_num_bis = ISO_MAX_NUM_BIS (31) and calling listen() will
eventually trigger hci_le_big_create_sync() from the HCI command
sync worker, causing a KASAN-detectable stack-out-of-bounds write:
BUG: KASAN: stack-out-of-bounds in hci_le_big_create_sync+0x256/0x3b0
Write of size 31 at addr ffffc90000487b48 by task kworker/u9:0/71
Fix this by changing the DEFINE_FLEX count from the incorrect 0x11 to
HCI_MAX_ISO_BIS, which matches the maximum number of BIS entries that
conn->bis can actually carry.
Severity
7.8 (High)
Assigner
References
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
91d19383b7ed035e22165ae5c836e50bb9f95fbe , < f5d446624345d309e7a4a1b27ea9f028d6a8c5d9
(git)
Affected: 42ecf1947135110ea08abeaca39741636f9a2285 , < aba0aea354015794e8312dd7efe726967e58aefe (git) Affected: 42ecf1947135110ea08abeaca39741636f9a2285 , < eaf32002ca7b1ba51c9f140991fd9febe6de79f0 (git) Affected: 42ecf1947135110ea08abeaca39741636f9a2285 , < bc39a094730ce062fa034a529c93147c096cb488 (git) Affected: 8958e1cee4e2eac1a5b825caa4dd96ce9ed975dd (git) Affected: 6.12.2 , < 6.12.81 (semver) Affected: 6.11.11 , < 6.12 (semver) |
guessed | |
| Linux | Linux |
Affected:
6.13
Unaffected: 0 , < 6.13 (semver) Unaffected: 6.12.81 , ≤ 6.12.* (semver) Unaffected: 6.18.22 , ≤ 6.18.* (semver) Unaffected: 6.19.12 , ≤ 6.19.* (semver) Unaffected: 7.0 , ≤ * (original_commit_for_fix) |
guessed |
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: hci_sync: fix stack buffer overflow in hci_le_big_create_sync\n\nhci_le_big_create_sync() uses DEFINE_FLEX to allocate a\nstruct hci_cp_le_big_create_sync on the stack with room for 0x11 (17)\nBIS entries. However, conn-\u003enum_bis can hold up to HCI_MAX_ISO_BIS (31)\nentries \u2014 validated against ISO_MAX_NUM_BIS (0x1f) in the caller\nhci_conn_big_create_sync(). When conn-\u003enum_bis is between 18 and 31,\nthe memcpy that copies conn-\u003ebis into cp-\u003ebis writes up to 14 bytes\npast the stack buffer, corrupting adjacent stack memory.\n\nThis is trivially reproducible: binding an ISO socket with\nbc_num_bis = ISO_MAX_NUM_BIS (31) and calling listen() will\neventually trigger hci_le_big_create_sync() from the HCI command\nsync worker, causing a KASAN-detectable stack-out-of-bounds write:\n\n BUG: KASAN: stack-out-of-bounds in hci_le_big_create_sync+0x256/0x3b0\n Write of size 31 at addr ffffc90000487b48 by task kworker/u9:0/71\n\nFix this by changing the DEFINE_FLEX count from the incorrect 0x11 to\nHCI_MAX_ISO_BIS, which matches the maximum number of BIS entries that\nconn-\u003ebis can actually carry."
}
],
"id": "CVE-2026-31772",
"lastModified": "2026-06-17T10:34:26.100",
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"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
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"current_release_date": "2026-07-12T09:50:56+00:00",
"cve": "CVE-2026-31772",
"id": "CVE-2026-31772",
"initial_release_date": "2026-05-01T00:00:00+00:00",
"product_status:fixed": "612",
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"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: Bluetooth: hci_sync: fix stack buffer overflow in hci_le_big_create_sync",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-31772.json",
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},
"suse_vex": {
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"current_release_date": "2026-08-15T23:54:13Z",
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"id": "CVE-2026-31772",
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"product_status:recommended": "172",
"source": "SUSE CSAF VEX",
"status": "interim",
"title": "SUSE CVE CVE-2026-31772",
"url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-31772.json",
"version": "5"
}
}
}
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Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
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- 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.
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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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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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