# CVE-2026-74734: firewire: ohci: fix NULL pointer dereference in ar_context_release

CVE-2026-74734 is fixed in linux on 1 platform, first by DEBIAN-CVE-2026-74734, released September 4, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-74734
- Priority: Routine
- CVSS: 5.5 (Moderate)
- EPSS: 0.0018
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Aug 26, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-74734

## Description

In the Linux kernel, the following vulnerability has been resolved:  firewire: ohci: fix NULL pointer dereference in ar_context_release  During the error handling path of the driver's probe function, a NULL pointer dereference can occur in ar_context_release().  When pci_probe() fails early (e.g., if pcim_enable_device() or MMIO mapping fails), the devres cleanup mechanism invokes release_ohci(). This function unconditionally calls ar_context_release() to clean up the asynchronous receive contexts. However, if ar_context_init() was not yet called, ctx->ohci remains NULL (as the fw_ohci structure is zero-initialized by devres_alloc()).  ar_context_release() immediately dereferences ctx->ohci to get the dev pointer before checking if the context was actually initialized, leading to a crash:  Oops: general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f] RIP: 0010:ar_context_release+0x3f/0x380 drivers/firewire/ohci.c:543 Call Trace:  release_ohci+0x3f/0x60 drivers/firewire/ohci.c:3567  release_nodes drivers/base/devres.c:546 [inline]  devres_release_all+0x1a8/0x260 drivers/base/devres.c:576  device_unbind_cleanup drivers/base/dd.c:597 [inline]  really_probe+0x451/0xae0 drivers/base/dd.c:772  To fix this, move the assignment of the dev pointer after the !ctx->buffer check. If ctx->buffer is NULL, it indicates that the context was never successfully initialized and there is nothing to release, safely avoiding the dereference of the uninitialized ctx->ohci pointer.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 13.5 (trixie) | 6.12.115-2 | [DEBIAN-CVE-2026-74734](https://patchblox.com/security/data/fix/linux/debian-cve-2026-74734.md) | Sep 4, 2026 |
| Linux | linux Debian 14 | 7.1.10-1 | [DEBIAN-CVE-2026-74734](https://patchblox.com/security/data/fix/linux/debian-cve-2026-74734.md) | Sep 4, 2026 |

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Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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