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CVE-2026-64403— Bluetooth: L2CAP: validate option length before reading conf opt value

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存在安全漏洞，该漏洞源于蓝牙L2CAP协议中选项长度验证顺序不当，在读取选项值之前未验证长度，导致越界读取（最多4字节）。

CVSS 7.1 · High EPSS 0.27% · P17

Possible ATT&CK Techniques 1 AI

T1203 · Exploitation for Client Execution

Affected Version Matrix 32

VendorProduct Version RangeStatus
Linux Linux 7c9cbd0b5e38a1672fcd137894ace3b042dfbf69< cca81b4bc672604a84f6d224a55cc77ec7dee619 affected
7c9cbd0b5e38a1672fcd137894ace3b042dfbf69< f70d4aa88068096f35d73e3a05eff33c0a16b9cd affected
7c9cbd0b5e38a1672fcd137894ace3b042dfbf69< 7d871e969b941ce25653f7716203a0ea4d07ad4b affected
7c9cbd0b5e38a1672fcd137894ace3b042dfbf69< 98d93c226bdfaa79bbdd86981921d7f106374225 affected
7c9cbd0b5e38a1672fcd137894ace3b042dfbf69< 996d3da39899aceb8f4910911a3f19a45a7d9d1b affected
7c9cbd0b5e38a1672fcd137894ace3b042dfbf69< 73abbaf91aa33da87c008fb62c148ade561bb606 affected
7c9cbd0b5e38a1672fcd137894ace3b042dfbf69< 6b47bdaacfd0045687880177e0987055d8f4765a affected
7c9cbd0b5e38a1672fcd137894ace3b042dfbf69< 687617555cedfb74c9e3cb85d759b908dcb17856 affected
… +24 more rows
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I. Basic Information for CVE-2026-64403

Vulnerability Information
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Vulnerability Title
Bluetooth: L2CAP: validate option length before reading conf opt value
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: validate option length before reading conf opt value l2cap_get_conf_opt() derives the option length from the attacker-controlled opt->len field and immediately dereferences opt->val (as u8, get_unaligned_le16() or get_unaligned_le32(), or a raw pointer for the default case) before any caller has confirmed that opt->len bytes are present in the buffer. The callers (l2cap_parse_conf_req(), l2cap_parse_conf_rsp() and l2cap_conf_rfc_get()) only detect a malformed option afterwards, once the running length has gone negative, by which point the out-of-bounds read has already executed. An existing post-hoc length check keeps the garbage value from being consumed, so this is not a data leak in the current control flow. It is still a validate-after-use ordering bug: up to 4 bytes are read past the end of the buffer before it is known to contain them, and it is fragile to future changes in the callers. Fix it at the source. Pass the end of the buffer into l2cap_get_conf_opt() and refuse to touch opt->val unless the full option (header + value) fits. Each caller computes an end pointer once before the loop and checks the return value directly instead of inferring the error from a negative length.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/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存在安全漏洞，该漏洞源于蓝牙L2CAP协议中选项长度验证顺序不当，在读取选项值之前未验证长度，导致越界读取（最多4字节）。
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 7c9cbd0b5e38a1672fcd137894ace3b042dfbf69 ~ cca81b4bc672604a84f6d224a55cc77ec7dee619 -
Linux Linux 5.1 -

II. Public POCs for CVE-2026-64403

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III. Intelligence Information for CVE-2026-64403

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Patches & Fixes for CVE-2026-64403 (8)

Same Patch Batch · Linux · 2026-07-25 · 274 CVEs total

CVE-2026-64355 9.8 CRITICAL bpf: Reject fragmented frames in devmap
CVE-2026-64459 9.8 CRITICAL tcp: restore RCU grace period in tcp_ao_destroy_sock
CVE-2026-64303 9.8 CRITICAL spi: fsl-lpspi: terminate the RX channel on TX prepare failure path
CVE-2026-64439 9.8 CRITICAL crypto: krb5 - filter out async aead implementations at alloc
CVE-2026-64410 9.8 CRITICAL netfilter: flowtable: IPIP tunnel hardware offload is not yet support
CVE-2026-64399 9.8 CRITICAL ksmbd: add permission checks for FSCTL_DUPLICATE_EXTENTS_TO_FILE
CVE-2026-64397 9.8 CRITICAL ksmbd: serialize QUERY_DIRECTORY requests per file
CVE-2026-64391 9.8 CRITICAL ksmbd: use opener credentials for ADS I/O
CVE-2026-64387 9.8 CRITICAL smb: client: fix query directory replay double-free
CVE-2026-64386 9.8 CRITICAL smb: client: fix query_info() replay double-free
CVE-2026-64385 9.8 CRITICAL smb: client: fix double-free in SMB2_ioctl() replay
CVE-2026-64383 9.8 CRITICAL smb: client: fix double-free in SMB2_flush() replay
CVE-2026-64384 9.8 CRITICAL smb: client: fix change notify replay double-free
CVE-2026-64268 9.8 CRITICAL RDMA/siw: bound Read Response placement to the RREAD length
CVE-2026-64523 9.8 CRITICAL net/handshake: Take a long-lived file reference at submit
CVE-2026-64269 9.1 CRITICAL RDMA/rtrs-srv: Bound RDMA-Write length to chunk size in rdma_write_sg
CVE-2026-64257 9.1 CRITICAL smb: client: reject overlapping data areas in SMB2 responses
CVE-2026-64319 9.1 CRITICAL nvmet-auth: validate reply message payload bounds against transfer length
CVE-2026-64320 9.1 CRITICAL nvmet: fix pre-auth out-of-bounds heap read in Discovery Get Log Page
CVE-2026-64393 9.1 CRITICAL ksmbd: run set info with opener credentials

Showing top 20 of 274 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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