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CVE-2025-21878: i2c: npcm: disable interrupt enable bit before devm_request_irq

In the Linux kernel, the following vulnerability has been resolved: i2c: npcm: disable interrupt enable bit before devm_request_irq The customer reports that there is a soft lockup issue related to the i2c driver. After checking, the i2c module was doing a tx transfer and the bmc machine reboots in the middle of the i2c transaction, the i2c module keeps the status without being reset. Due to such an i2c module status, the i2c irq handler keeps getting triggered since the i2c irq handler is registered in the kernel booting process after the bmc machine is doing a warm rebooting. The continuous triggering is stopped by the soft lockup watchdog timer. Disable the interrupt enable bit in the i2c module before calling devm_request_irq to fix this issue since the i2c relative status bit is read-only. Here is the soft lockup log. [ 28.176395] watchdog: BUG: soft lockup - CPU#0 stuck for 26s! [swapper/0:1] [ 28.183351] Modules linked in: [ 28.186407] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.15.120-yocto-s-dirty-bbebc78 #1 [ 28.201174] pstate: 40000005 (nZcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) [ 28.208128] pc : __do_softirq+0xb0/0x368 [ 28.212055] lr : __do_softirq+0x70/0x368 [ 28.215972] sp : ffffff8035ebca00 [ 28.219278] x29: ffffff8035ebca00 x28: 0000000000000002 x27: ffffff80071a3780 [ 28.226412] x26: ffffffc008bdc000 x25: ffffffc008bcc640 x24: ffffffc008be50c0 [ 28.233546] x23: ffffffc00800200c x22: 0000000000000000 x21: 000000000000001b [ 28.240679] x20: 0000000000000000 x19: ffffff80001c3200 x18: ffffffffffffffff [ 28.247812] x17: ffffffc02d2e0000 x16: ffffff8035eb8b40 x15: 00001e8480000000 [ 28.254945] x14: 02c3647e37dbfcb6 x13: 02c364f2ab14200c x12: 0000000002c364f2 [ 28.262078] x11: 00000000fa83b2da x10: 000000000000b67e x9 : ffffffc008010250 [ 28.269211] x8 : 000000009d983d00 x7 : 7fffffffffffffff x6 : 0000036d74732434 [ 28.276344] x5 : 00ffffffffffffff x4 : 0000000000000015 x3 : 0000000000000198 [ 28.283476] x2 : ffffffc02d2e0000 x1 : 00000000000000e0 x0 : ffffffc008bdcb40 [ 28.290611] Call trace: [ 28.293052] __do_softirq+0xb0/0x368 [ 28.296625] __irq_exit_rcu+0xe0/0x100 [ 28.300374] irq_exit+0x14/0x20 [ 28.303513] handle_domain_irq+0x68/0x90 [ 28.307440] gic_handle_irq+0x78/0xb0 [ 28.311098] call_on_irq_stack+0x20/0x38 [ 28.315019] do_interrupt_handler+0x54/0x5c [ 28.319199] el1_interrupt+0x2c/0x4c [ 28.322777] el1h_64_irq_handler+0x14/0x20 [ 28.326872] el1h_64_irq+0x74/0x78 [ 28.330269] __setup_irq+0x454/0x780 [ 28.333841] request_threaded_irq+0xd0/0x1b4 [ 28.338107] devm_request_threaded_irq+0x84/0x100 [ 28.342809] npcm_i2c_probe_bus+0x188/0x3d0 [ 28.346990] platform_probe+0x6c/0xc4 [ 28.350653] really_probe+0xcc/0x45c [ 28.354227] __driver_probe_device+0x8c/0x160 [ 28.358578] driver_probe_device+0x44/0xe0 [ 28.362670] __driver_attach+0x124/0x1d0 [ 28.366589] bus_for_each_dev+0x7c/0xe0 [ 28.370426] driver_attach+0x28/0x30 [ 28.373997] bus_add_driver+0x124/0x240 [ 28.377830] driver_register+0x7c/0x124 [ 28.381662] __platform_driver_register+0x2c/0x34 [ 28.386362] npcm_i2c_init+0x3c/0x5c [ 28.389937] do_one_initcall+0x74/0x230 [ 28.393768] kernel_init_freeable+0x24c/0x2b4 [ 28.398126] kernel_init+0x28/0x130 [ 28.401614] ret_from_fork+0x10/0x20 [ 28.405189] Kernel panic - not syncing: softlockup: hung tasks [ 28.411011] SMP: stopping secondary CPUs [ 28.414933] Kernel Offset: disabled [ 28.418412] CPU features: 0x00000000,00000802 [ 28.427644] Rebooting in 20 seconds..

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2025-21878 is a Linux kernel availability bug affecting the NPCM I2C driver, commonly relevant to BMC platforms. A warm reboot during an I2C transfer can leave hardware state uncleared, causing repeated interrupts, a soft lockup, and kernel panic during boot.

Executive priority

Treat this as a targeted availability risk for BMC and embedded Linux fleets, not a broad internet-facing emergency. Patch during the next appropriate maintenance window, faster where BMC reboot reliability is operationally critical.

Technical view

The NPCM I2C driver registered its IRQ while an interrupt-enable bit could still be set after a warm reboot. Because related status bits are read-only, the IRQ handler can be repeatedly invoked during probe. The upstream fix disables the interrupt-enable bit before devm_request_irq.

Likely exposure

Exposure appears limited to Linux systems using the NPCM I2C driver on affected kernel versions or downstream kernels carrying the vulnerable code. The source lists affected Linux versions including 5.8, 5.10.235, 5.15.179, 6.1.130, 6.6.81, 6.12.18, 6.13.6, and 6.14.

Exploitation context

The provided sources do not show active exploitation, and KEV is false. The described trigger is operational: a BMC warm reboot during an I2C transaction can leave stale module state and cause a boot-time interrupt storm. No remote attack path is established in the bundle.

Researcher notes

The source data has no CVSS, CWE, or confirmed exploitation. Analysis should focus on kernel lineage, downstream backports, and whether deployed hardware uses the NPCM I2C path. Avoid assuming impact on systems without this driver or affected code.

Mitigation direction

  • Apply vendor or distribution kernel updates containing the listed stable fixes.
  • For Debian LTS systems, review the referenced Debian advisories and update packages accordingly.
  • Prioritize BMC or embedded platforms using the NPCM I2C driver.
  • If no vendor fix is available, ask the vendor for backport guidance.

Validation and detection

  • Inventory systems running Linux kernels in the affected version list.
  • Confirm whether the NPCM I2C driver is present and used on each platform.
  • Review boot logs for soft lockup, IRQ storm, or NPCM I2C probe failures.
  • Map installed kernel builds to the referenced stable commit fixes.
  • Check distribution advisories for backported package versions.
Prepared
Confidence
medium
Sources
11

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
1ADP providers
10Source links

Vulnerability timeline

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  2. CVE publishedCVE Program

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  3. CVE updatedCVE Program

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Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux56a1485b102ed1cd5a4af8e87ed794699fd1cad2, 56a1485b102ed1cd5a4af8e87ed794699fd1cad2, 56a1485b102ed1cd5a4af8e87ed794699fd1cad2, 56a1485b102ed1cd5a4af8e87ed794699fd1cad2, 56a1485b102ed1cd5a4af8e87ed794699fd1cad2, 56a1485b102ed1cd5a4af8e87ed794699fd1cad2, 56a1485b102ed1cd5a4af8e87ed794699fd1cad2unaffected
LinuxLinux5.8, 0, 5.10.235, 5.15.179, 6.1.130, 6.6.81, 6.12.18, 6.13.6, 6.14affected
Weakness

CWE details

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