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Linux Kernel CVE-2026-31772

| EUVDEUVD-2026-26585 HIGH
Out-of-bounds Write (CWE-787)
2026-05-01 Linux
Red Hat Suse Buffer Overflow Linux Memory Corruption
7.8
CVSS 3.1 · NVD
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Severity by source

NVD PRIMARY
7.8 HIGH
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
SUSE
HIGH
qualitative
Red Hat
7.0 MEDIUM
qualitative

Primary rating from NVD.

CVSS VectorNVD

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

5
Analysis Generated
May 03, 2026 - 07:31 vuln.today
CVSS changed
May 03, 2026 - 07:22 NVD
7.8 (HIGH)
EUVD ID Assigned
May 01, 2026 - 15:00 euvd
EUVD-2026-26585
Analysis Generated
May 01, 2026 - 15:00 vuln.today
CVE Published
May 01, 2026 - 14:15 nvd
HIGH 7.8

DescriptionCVE.org

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.

AnalysisAI

Stack buffer overflow in Linux kernel Bluetooth subsystem allows local authenticated attackers to achieve code execution, privilege escalation, or denial of service through malformed ISO socket parameters. The vulnerability occurs when binding an ISO Bluetooth socket with up to 31 BIS entries while the hci_le_big_create_sync() function only allocates stack space for 17 entries, resulting in a 14-byte overflow that corrupts adjacent stack memory. Patches are available across multiple kernel versions (6.12.81, 6.18.22, 6.19.12, 7.0), with EPSS indicating 0.02% exploitation probability and no active exploitation confirmed.

Technical ContextAI

This vulnerability affects the Linux kernel's Bluetooth HCI (Host Controller Interface) synchronization layer, specifically in ISO (Isochronous) socket handling for BIS (Broadcast Isochronous Stream) connections. The flaw stems from a size mismatch between allocated stack memory and actual data structure capacity. The hci_le_big_create_sync() function uses DEFINE_FLEX to create a stack-allocated struct hci_cp_le_big_create_sync with space for only 0x11 (17) BIS entries, but the conn->num_bis field can hold up to HCI_MAX_ISO_BIS (31) entries, validated against ISO_MAX_NUM_BIS (0x1f) in the caller function hci_conn_big_create_sync(). When conn->num_bis contains 18-31 entries, the subsequent memcpy operation writing conn->bis into cp->bis overflows the allocated stack buffer by up to 14 bytes, corrupting adjacent stack memory. This is a classic stack-based buffer overflow, categorized under CWE-121 (Stack-based Buffer Overflow), though no CWE was officially assigned. The vulnerability was detected using KASAN (Kernel Address Sanitizer) during testing, indicating kernel memory safety tooling can identify this class of error.

RemediationAI

Upgrade to patched Linux kernel versions: 6.12.81 or later for the 6.12.x series, 6.18.22 or later for 6.18.x, 6.19.12 or later for 6.19.x, or version 7.0 and above. The fix changes the DEFINE_FLEX allocation count from 0x11 to HCI_MAX_ISO_BIS (31), ensuring sufficient stack space for the maximum possible BIS entries. Patch commits are available at https://git.kernel.org/stable/c/f5d446624345d309e7a4a1b27ea9f028d6a8c5d9 (mainline fix), with backports at https://git.kernel.org/stable/c/aba0aea354015794e8312dd7efe726967e58aefe, https://git.kernel.org/stable/c/eaf32002ca7b1ba51c9f140991fd9febe6de79f0, and https://git.kernel.org/stable/c/bc39a094730ce062fa034a529c93147c096cb488. If immediate patching is not feasible, disable Bluetooth ISO socket functionality by preventing unprivileged users from creating AF_BLUETOOTH/BTPROTO_ISO sockets through sysctl net.bluetooth.iso_socket_restrict=1 or similar access controls - this eliminates the attack vector but breaks legitimate Bluetooth audio applications requiring BIS/CIS functionality. Alternatively, restrict CAP_NET_ADMIN capability to trusted users only, though this does not fully mitigate the risk since PR:L indicates low-privilege access suffices. Monitor for abnormal ISO socket creation patterns in audit logs. Note that disabling Bluetooth entirely prevents exploitation but may impact operational requirements for Bluetooth-dependent systems.

Same weakness CWE-787 – Out-of-bounds Write

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Same technique Buffer Overflow

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CVE-2017-7269 CRITICAL POC
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Vendor StatusVendor

SUSE

Severity: High
Product Status
SUSE Linux Enterprise Desktop 15 SP7 Fixed
SUSE Linux Enterprise Desktop 15 SP7 Fixed
SUSE Linux Enterprise High Availability Extension 15 SP7 Fixed
SUSE Linux Enterprise High Availability Extension 15 SP7 Fixed
SUSE Linux Enterprise High Performance Computing 15 SP7 Fixed

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CVE-2026-31772 vulnerability details – vuln.today
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