Linux Kernel up to 6.19.13 mcp23s08 _raw_spin_lock_irq denial of service

Summaryinfo

A vulnerability, which was classified as critical, has been found in Linux Kernel up to 6.19.13. The impacted element is the function _raw_spin_lock_irq of the component mcp23s08. The manipulation leads to denial of service. This vulnerability is listed as CVE-2026-43087. There is no available exploit. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.19.13. It has been rated as critical. This issue affects the function _raw_spin_lock_irq of the component mcp23s08. The manipulation with an unknown input leads to a denial of service vulnerability. Using CWE to declare the problem leads to CWE-404. The product does not release or incorrectly releases a resource before it is made available for re-use. Impacted is availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: pinctrl: mcp23s08: Disable all pin interrupts during probe A chip being probed may have the interrupt-on-change feature enabled on some of its pins, for example after a reboot. This can cause the chip to generate interrupts for pins that don't have a registered nested handler, which leads to a kernel crash such as below: [ 7.928897] Unable to handle kernel read from unreadable memory at virtual address 00000000000000ac [ 7.932314] Mem abort info: [ 7.935081] ESR = 0x0000000096000004 [ 7.938808] EC = 0x25: DABT (current EL), IL = 32 bits [ 7.944094] SET = 0, FnV = 0 [ 7.947127] EA = 0, S1PTW = 0 [ 7.950247] FSC = 0x04: level 0 translation fault [ 7.955101] Data abort info: [ 7.957961] ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000 [ 7.963421] CM = 0, WnR = 0, TnD = 0, TagAccess = 0 [ 7.968447] GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 [ 7.973734] user pgtable: 4k pages, 48-bit VAs, pgdp=00000000089b7000 [ 7.980148] [00000000000000ac] pgd=0000000000000000, p4d=0000000000000000 [ 7.986913] Internal error: Oops: 0000000096000004 [#1] SMP [ 7.992545] Modules linked in: [ 8.073678] CPU: 0 UID: 0 PID: 81 Comm: irq/18-4-0025 Not tainted 7.0.0-rc6-gd2b5a1f931c8-dirty #199 [ 8.073689] Hardware name: Khadas VIM3 (DT) [ 8.073692] pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--) [ 8.094639] pc : _raw_spin_lock_irq+0x40/0x80 [ 8.098970] lr : handle_nested_irq+0x2c/0x168 [ 8.098979] sp : ffff800082b2bd20 [ 8.106599] x29: ffff800082b2bd20 x28: ffff800080107920 x27: ffff800080104d88 [ 8.106611] x26: ffff000003298080 x25: 0000000000000001 x24: 000000000000ff00 [ 8.113707] x23: 0000000000000001 x22: 0000000000000000 x21: 000000000000000e [ 8.120850] x20: 0000000000000000 x19: 00000000000000ac x18: 0000000000000000 [ 8.135046] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000 [ 8.135062] x14: ffff800081567ea8 x13: ffffffffffffffff x12: 0000000000000000 [ 8.135070] x11: 00000000000000c0 x10: 0000000000000b60 x9 : ffff800080109e0c [ 8.135078] x8 : 1fffe0000069dbc1 x7 : 0000000000000001 x6 : ffff0000034ede00 [ 8.135086] x5 : 0000000000000000 x4 : ffff0000034ede08 x3 : 0000000000000001 [ 8.163460] x2 : 0000000000000000 x1 : 0000000000000001 x0 : 00000000000000ac [ 8.170560] Call trace: [ 8.180094] _raw_spin_lock_irq+0x40/0x80 (P) [ 8.184443] mcp23s08_irq+0x248/0x358 [ 8.184462] irq_thread_fn+0x34/0xb8 [ 8.184470] irq_thread+0x1a4/0x310 [ 8.195093] kthread+0x13c/0x150 [ 8.198309] ret_from_fork+0x10/0x20 [ 8.201850] Code: d65f03c0 d2800002 52800023 f9800011 (885ffc01) [ 8.207931] ---[ end trace 0000000000000000 ]--- This issue has always been present, but has been latent until commit "f9f4fda15e72" ("pinctrl: mcp23s08: init reg_defaults from HW at probe and switch cache type"), which correctly removed reg_defaults from the regmap and as a side effect changed the behavior of the interrupt handler so that the real value of the MCP_GPINTEN register is now being read from the chip instead of using a bogus 0 default value; a non-zero value for this register can trigger the invocation of a nested handler which may not exist (yet). Fix this issue by disabling all pin interrupts during initialization.

The advisory is shared at git.kernel.org. The identification of this vulnerability is CVE-2026-43087 since 05/01/2026. The exploitation is known to be difficult. Technical details are known, but no exploit is available.

Upgrading to version 6.19.14 eliminates this vulnerability. Applying the patch f8c3258541a0680a4ebc08b05b2bc5fdad3288a9/db5b8cecbdf479ad13156af750377e5b43853fab is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2026-1385). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Affected

• Google Container-Optimized OS
• Debian Linux
• Red Hat Enterprise Linux
• Ubuntu Linux
• SUSE Linux
• Oracle Linux
• SUSE openSUSE
• Open Source Linux Kernel
• RESF Rocky Linux
• Microsoft Azure Linux

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.19.0
• 6.19.1
• 6.19.2
• 6.19.3
• 6.19.4
• 6.19.5
• 6.19.6
• 6.19.7
• 6.19.8
• 6.19.9
• 6.19.10
• 6.19.11
• 6.19.12
• 6.19.13

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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Sourcesinfo

Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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