Vulnerability Details CVE-2026-31513
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: L2CAP: Fix stack-out-of-bounds read in l2cap_ecred_conn_req
Syzbot reported a KASAN stack-out-of-bounds read in l2cap_build_cmd()
that is triggered by a malformed Enhanced Credit Based Connection Request.
The vulnerability stems from l2cap_ecred_conn_req(). The function allocates
a local stack buffer (`pdu`) designed to hold a maximum of 5 Source Channel
IDs (SCIDs), totaling 18 bytes. When an attacker sends a request with more
than 5 SCIDs, the function calculates `rsp_len` based on this unvalidated
`cmd_len` before checking if the number of SCIDs exceeds
L2CAP_ECRED_MAX_CID.
If the SCID count is too high, the function correctly jumps to the
`response` label to reject the packet, but `rsp_len` retains the
attacker's oversized value. Consequently, l2cap_send_cmd() is instructed
to read past the end of the 18-byte `pdu` buffer, triggering a
KASAN panic.
Fix this by moving the assignment of `rsp_len` to after the `num_scid`
boundary check. If the packet is rejected, `rsp_len` will safely
remain 0, and the error response will only read the 8-byte base header
from the stack.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.0
EPSS Ranking 5.7%
CVSS Severity
CVSS v3 Score 8.1
Products affected by CVE-2026-31513
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cpe:2.3:o:linux:linux_kernel:6.12.75
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cpe:2.3:o:linux:linux_kernel:6.12.77
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cpe:2.3:o:linux:linux_kernel:6.12.78
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cpe:2.3:o:linux:linux_kernel:6.18.16
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cpe:2.3:o:linux:linux_kernel:6.18.17
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cpe:2.3:o:linux:linux_kernel:6.18.18
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cpe:2.3:o:linux:linux_kernel:6.18.19
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cpe:2.3:o:linux:linux_kernel:6.18.20
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cpe:2.3:o:linux:linux_kernel:6.19.10
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cpe:2.3:o:linux:linux_kernel:6.19.6
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cpe:2.3:o:linux:linux_kernel:6.19.7
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cpe:2.3:o:linux:linux_kernel:6.19.8
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cpe:2.3:o:linux:linux_kernel:6.19.9