Linux Kernel up to 7.3-rc4 RFCOMM rfcomm_sock_getsockopt null pointer dereference

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6.2	$0-$5k	0.46-

Summaryinfo

A vulnerability categorized as critical has been discovered in Linux Kernel up to 7.3-rc4. Affected is the function rfcomm_sock_getsockopt of the component RFCOMM. Such manipulation leads to null pointer dereference. This vulnerability is uniquely identified as CVE-2026-98455. The attack can be launched remotely. No exploit exists. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 7.3-rc4 and classified as critical. Affected by this issue is the function rfcomm_sock_getsockopt of the component RFCOMM. The manipulation with an unknown input leads to a null pointer dereference vulnerability. Using CWE to declare the problem leads to CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. Impacted is availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: RFCOMM: fix NULL dereference of dlc->session in RFCOMM_CONNINFO The RFCOMM_CONNINFO getsockopt handler accepts a socket that is not connected as long as deferred setup is enabled: if (sk->sk_state != BT_CONNECTED && !rfcomm_pi(sk)->dlc->defer_setup) { err = -ENOTCONN; break; } l2cap_sk = rfcomm_pi(sk)->dlc->session->sock->sk; dlc->defer_setup is set in rfcomm_sock_init() when rfcomm_connect_ind() creates a child socket for an incoming connection on a listening socket that has BT_DEFER_SETUP enabled. It is never cleared afterwards. The session, however, can go away underneath it. rfcomm_recv_disc() forces the dlc state before tearing it down: d->state = BT_CLOSED; __rfcomm_dlc_close(d, err); The RFCOMM_DEFER_SETUP early return in __rfcomm_dlc_close() only covers BT_CONNECT, BT_CONFIG, BT_OPEN and BT_CONNECT2, so with the state already BT_CLOSED that switch does not match and the function falls through to rfcomm_dlc_unlink(), which sets d->session = NULL, while d->defer_setup stays 1. A getsockopt(SOL_RFCOMM, RFCOMM_CONNINFO) on the accepted socket after that point therefore skips the -ENOTCONN path -- sk->sk_state is BT_CLOSED, but dlc->defer_setup is still set -- and dereferences the NULL session. No race is needed: once the DISC has been processed, the dereference is unconditional. Reproduced on a KASAN kernel under QEMU with a BR/EDR peer emulated over /dev/vhci: the peer brings up an ACL link, opens L2CAP on the RFCOMM PSM, starts a session and sends SABM for a channel bound with BT_DEFER_SETUP, and sends DISC for that dlci after the socket has been accepted. getsockopt(SOL_RFCOMM, RFCOMM_CONNINFO) on the accepted socket then hits: Oops: general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] SMP KASAN PTI KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017] CPU: 1 UID: 0 PID: 150 Comm: init Tainted: G B 7.3.0-rc3-g5dd1818b15d9 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) RIP: 0010:rfcomm_sock_getsockopt+0x529/0x780 Call Trace: <TASK> do_sock_getsockopt+0x3ad/0x7d0 __sys_getsockopt+0x10e/0x1b0 __x64_sys_getsockopt+0xc2/0x160 do_syscall_64+0xda/0x4b0 entry_SYSCALL_64_after_hwframe+0x77/0x7f </TASK> 0x10 is the offset of sock in struct rfcomm_session; rfcomm_sock_getsockopt_old() is inlined into rfcomm_sock_getsockopt(). Commit 43a556b2fd43 ("Bluetooth: RFCOMM: take rfcomm_mutex for the deferred setup accept") fixed the same "a remote DISC clears the session while deferred setup is still flagged" problem in rfcomm_dlc_accept(); this is the remaining instance of it, in the getsockopt path. Deferred setup only leaves a socket usable here once it has reached BT_CONNECT2, so restrict the exception to that state and check that a session is actually present before following it.

The advisory is shared for download at git.kernel.org. This vulnerability is handled as CVE-2026-98455 since 09/25/2026. The exploitation is known to be easy. The attack may be launched remotely. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 10/18/2026).

Upgrading to version 5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.112, 6.18.55, 7.2.9 or 7.3-rc5 eliminates this vulnerability. Applying the patch c3aee3fc1287c8a555baf3895959087cb0c33fe8/4bf5ca47203049ce3648f750a53dcdc98bcc9e3e/1c4f7e1177da2f229be04139c27e5370a1cfba52/84ae3cfd7d3a63591a2eb4faa24faf678c6708aa/c7362f6a18ed167f52f08ce25eeec8a7818c5004/8f5b30cc12c409ff62891e47ed51e6bf0945a3ea/005b23d9e324fe5d0acbcfa70c625f2e81189046/46f8ffd0a1f1eb6cbc94946a92c11ef601e228a1 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 5.10.270
• 5.15.221
• 6.1.188
• 6.6.157
• 6.12.111
• 6.18.0
• 6.18.1
• 6.18.2
• 6.18.3
• 6.18.4
• 6.18.5
• 6.18.6
• 6.18.7
• 6.18.8
• 6.18.9
• 6.18.10
• 6.18.11
• 6.18.12
• 6.18.13
• 6.18.14
• 6.18.15
• 6.18.16
• 6.18.17
• 6.18.18
• 6.18.19
• 6.18.20
• 6.18.21
• 6.18.22
• 6.18.23
• 6.18.24
• 6.18.25
• 6.18.26
• 6.18.27
• 6.18.28
• 6.18.29
• 6.18.30
• 6.18.31
• 6.18.32
• 6.18.33
• 6.18.34
• 6.18.35
• 6.18.36
• 6.18.37
• 6.18.38
• 6.18.39
• 6.18.40
• 6.18.41
• 6.18.42
• 6.18.43
• 6.18.44
• 6.18.45
• 6.18.46
• 6.18.47
• 6.18.48
• 6.18.49
• 6.18.50
• 6.18.51
• 6.18.52
• 6.18.53
• 6.18.54
• 7.2.0
• 7.2.1
• 7.2.2
• 7.2.3
• 7.2.4
• 7.2.5
• 7.2.6
• 7.2.7
• 7.2.8
• 7.3-rc1
• 7.3-rc2
• 7.3-rc3
• 7.3-rc4

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

• 🔒
• 🔒
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CPE 2.2info

• 🔒
• 🔒
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CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.5
VulDB Meta Temp Score: 6.2

VulDB Base Score: 6.5
VulDB Temp Score: 6.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Null pointer dereference
CWE: CWE-476 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.10.271/5.15.222/6.1.189/6.6.158/6.12.112/6.18.55/7.2.9/7.3-rc5
Patch: c3aee3fc1287c8a555baf3895959087cb0c33fe8/4bf5ca47203049ce3648f750a53dcdc98bcc9e3e/1c4f7e1177da2f229be04139c27e5370a1cfba52/84ae3cfd7d3a63591a2eb4faa24faf678c6708aa/c7362f6a18ed167f52f08ce25eeec8a7818c5004/8f5b30cc12c409ff62891e47ed51e6bf0945a3ea/005b23d9e324fe5d0acbcfa70c625f2e81189046/46f8ffd0a1f1eb6cbc94946a92c11ef601e228a1

Timelineinfo

09/25/2026 CVE reserved
10/18/2026 +23 days Advisory disclosed
10/18/2026 +0 days VulDB entry created
10/18/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-98455 (🔒)
GCVE (CVE): GCVE-0-2026-98455
GCVE (VulDB): GCVE-100-421772

Entryinfo

Created: 10/18/2026 17:34
Changes: 10/18/2026 17:34 (59)
Complete: 🔍
Cache ID: 216::103

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Discussion

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