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CVE-2026-31773— Bluetooth: SMP: derive legacy responder STK authentication from MITM state

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基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于蓝牙SMP协议中STK认证状态未正确反映MITM状态，可能导致密钥元数据与配对结果不匹配。

CVSS 8.8 · High EPSS 0.28% · P19

Affected Version Matrix 20

VendorProduct Version RangeStatus
Linux Linux fff3490f47810e2d34b91fb9e31103e923b11c2f< 9a38659a3d06080715691bd3139f9c4b61f688e3 affected
fff3490f47810e2d34b91fb9e31103e923b11c2f< 667f44f1392df6482483756458c48670e579e9ff affected
fff3490f47810e2d34b91fb9e31103e923b11c2f< 929db734d12db41ca5f95424db4612397f1bd4a7 affected
fff3490f47810e2d34b91fb9e31103e923b11c2f< b1c6a8e554a39b222c0879a288ea98e338fc4d77 affected
fff3490f47810e2d34b91fb9e31103e923b11c2f< 0afc846bd80073ffcd2b8040f2b2fafaea3d9f72 affected
fff3490f47810e2d34b91fb9e31103e923b11c2f< 061ee71ac6b03c9f8432fe49538c3682bfcf4cf3 affected
fff3490f47810e2d34b91fb9e31103e923b11c2f< 9a6d0db176f082685e0b6149700c0baf3ce2aa8b affected
fff3490f47810e2d34b91fb9e31103e923b11c2f< 20756fec2f0108cb88e815941f1ffff88dc286fe affected
… +12 more rows
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I. Basic Information for CVE-2026-31773

Vulnerability Information
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Vulnerability Title
Bluetooth: SMP: derive legacy responder STK authentication from MITM state
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: SMP: derive legacy responder STK authentication from MITM state The legacy responder path in smp_random() currently labels the stored STK as authenticated whenever pending_sec_level is BT_SECURITY_HIGH. That reflects what the local service requested, not what the pairing flow actually achieved. For Just Works/Confirm legacy pairing, SMP_FLAG_MITM_AUTH stays clear and the resulting STK should remain unauthenticated even if the local side requested HIGH security. Use the established MITM state when storing the responder STK so the key metadata matches the pairing result. This also keeps the legacy path aligned with the Secure Connections code, which already treats JUST_WORKS/JUST_CFM as unauthenticated.
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基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于蓝牙SMP协议中STK认证状态未正确反映MITM状态，可能导致密钥元数据与配对结果不匹配。
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 fff3490f47810e2d34b91fb9e31103e923b11c2f ~ 9a38659a3d06080715691bd3139f9c4b61f688e3 -
Linux Linux 3.16 -

II. Public POCs for CVE-2026-31773

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III. Intelligence Information for CVE-2026-31773

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Patches & Fixes for CVE-2026-31773 (8)

Same Patch Batch · Linux · 2026-05-01 · 146 CVEs total

CVE-2026-43037 9.8 CRITICAL ip6_tunnel: clear skb2->cb[] in ip4ip6_err()
CVE-2026-43011 9.8 CRITICAL net/x25: Fix potential double free of skb
CVE-2026-31705 9.8 CRITICAL ksmbd: fix out-of-bounds write in smb2_get_ea() EA alignment
CVE-2026-43038 9.8 CRITICAL ipv6: icmp: clear skb2->cb[] in ip6_err_gen_icmpv6_unreach()
CVE-2026-43039 9.8 CRITICAL net: ti: icssg-prueth: fix missing data copy and wrong recycle in ZC RX dispatch
CVE-2026-31718 9.8 CRITICAL ksmbd: fix use-after-free in __ksmbd_close_fd() via durable scavenger
CVE-2026-43018 8.8 HIGH Bluetooth: hci_event: fix potential UAF in hci_le_remote_conn_param_req_evt
CVE-2026-31739 8.8 HIGH crypto: tegra - Add missing CRYPTO_ALG_ASYNC
CVE-2026-31706 8.8 HIGH ksmbd: validate num_aces and harden ACE walk in smb_inherit_dacl()
CVE-2026-31709 8.8 HIGH smb: client: validate the whole DACL before rewriting it in cifsacl
CVE-2026-43048 8.8 HIGH HID: core: Mitigate potential OOB by removing bogus memset()
CVE-2026-31735 8.8 HIGH iommupt: Fix short gather if the unmap goes into a large mapping
CVE-2026-31717 8.8 HIGH ksmbd: validate owner of durable handle on reconnect
CVE-2026-31712 8.3 HIGH ksmbd: require minimum ACE size in smb_check_perm_dacl()
CVE-2026-31771 8.1 HIGH Bluetooth: hci_event: move wake reason storage into validated event handlers
CVE-2026-43051 8.1 HIGH HID: wacom: fix out-of-bounds read in wacom_intuos_bt_irq
CVE-2026-31708 8.1 HIGH smb: client: fix OOB read in smb2_ioctl_query_info QUERY_INFO path
CVE-2026-31779 8.1 HIGH wifi: iwlwifi: mvm: fix potential out-of-bounds read in iwl_mvm_nd_match_info_handler()
CVE-2026-43019 7.8 HIGH Bluetooth: hci_conn: fix potential UAF in set_cig_params_sync
CVE-2026-31772 7.8 HIGH Bluetooth: hci_sync: fix stack buffer overflow in hci_le_big_create_sync

Showing top 20 of 146 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-31773

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