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CVE-2026-64557— Bluetooth: L2CAP: Fix use-after-free in l2cap_sock_new_connection_cb()

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会开源的一款操作系统内核。 Linux kernel 3.13版本存在安全漏洞，该漏洞源于Bluetooth L2CAP中l2cap_sock_new_connection_cb()函数在释放父锁后返回chan，导致其他任务可以接受并释放子socket，造成释放后重用。

CVSS 8.8 · High EPSS 0.24% · P14

Possible ATT&CK Techniques 1 AI

T1059 · Command and Scripting Interpreter

Affected Version Matrix 14

VendorProduct Version RangeStatus
Linux Linux 8ffb929098a56939ac71509302eeab5b207bf262< b39298044e5534612511a2ff5de03ba5f6e7a820 affected
8ffb929098a56939ac71509302eeab5b207bf262< 8c37e4338c801ebb8cee52436c01c41e009f6e87 affected
8ffb929098a56939ac71509302eeab5b207bf262< 84e718b6a814edc84159361f9f454a4e92ae91ae affected
8ffb929098a56939ac71509302eeab5b207bf262< 36da806f7fbaee56ad9e81859deec203f9728700 affected
8ffb929098a56939ac71509302eeab5b207bf262< 733e76e74e406c1d1ddc7369420dd8a47f48bb8a affected
8ffb929098a56939ac71509302eeab5b207bf262< 6fef032af0092ed5ccb767239a9ac1bc38c08a40 affected
3.13 affected
< 3.13 unaffected
… +6 more rows
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I. Basic Information for CVE-2026-64557

Vulnerability Information
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Vulnerability Title
Bluetooth: L2CAP: Fix use-after-free in l2cap_sock_new_connection_cb()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: Fix use-after-free in l2cap_sock_new_connection_cb() l2cap_sock_new_connection_cb() returned l2cap_pi(sk)->chan after release_sock(parent). Once the parent lock is dropped the newly enqueued child socket sk is reachable via the accept queue, so another task can accept and free it before the callback dereferences sk, resulting in a use-after-free. Rework the ->new_connection() op so the core, rather than the callback, owns the child channel's lifetime. The op now receives a pre-allocated new_chan and returns an errno instead of allocating and returning a channel. l2cap_new_connection() allocates the child channel and links it into the conn list via __l2cap_chan_add() before invoking the callback, so the conn-list reference keeps the channel alive once release_sock(parent) exposes the socket to other tasks. Channel configuration that was duplicated in l2cap_sock_init() and the various new_connection callbacks is consolidated into l2cap_chan_set_defaults(), which now inherits from the parent channel when one is supplied.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会开源的一款操作系统内核。 Linux kernel 3.13版本存在安全漏洞，该漏洞源于Bluetooth L2CAP中l2cap_sock_new_connection_cb()函数在释放父锁后返回chan，导致其他任务可以接受并释放子socket，造成释放后重用。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 8ffb929098a56939ac71509302eeab5b207bf262 ~ b39298044e5534612511a2ff5de03ba5f6e7a820 -
Linux Linux 3.13 -

II. Public POCs for CVE-2026-64557

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III. Intelligence Information for CVE-2026-64557

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Patches & Fixes for CVE-2026-64557 (6)

Same Patch Batch · Linux · 2026-07-29 · 5 CVEs total

CVE-2026-64556 7.8 HIGH perf/core: Detach event groups during remove_on_exec
CVE-2026-64559 7.8 HIGH s390/pkey: Check length in PKEY_VERIFYPROTK ioctl
CVE-2026-64558 7.8 HIGH s390/pkey: Check length in pkey_pckmo handler implementation
CVE-2026-64560 7.8 HIGH posix-cpu-timers: Prevent UAF caused by non-leader exec() race

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-64557

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