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CVE-2026-74411
wifi: rtw89: Correct data type for scan index to avoid infinite loop
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem drivers/net. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-74411 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| Debian 13trixie | fixed | 6.12.100-1 | Update the kernel and reboot. Fixed in 6.12.100-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
A kernel soft lockup was observed during Wi-Fi scanning on the 6GHz band. The CPU becomes stuck in rtw89_hw_scan_add_chan_ax for over 20 seconds, leading to a system panic. RIP points to 0f b6 c3 (movzbl %bl, %eax), which zero-extends the low 8 bits of RBX into RAX. RBX (the counter i) has reached a huge value: 0x137466a1. watchdog: BUG: soft lockup - CPU#2 stuck for 26s! [kworker/u16:4:6124] Workqueue: events_unbound cfg80211_wiphy_work [cfg80211] RIP: 0010:rtw89_hw_scan_add_chan_ax+0xb3/0x6e0 [rtw89_core] Code: a0 48 89 45 a8 44 89 6d 9c 44 89 75 98 eb 29 66 66 2e 0f 1f 84 00 00 00 00 00 66 66 2e 0f 1f 84 00 00 00 00 00 66 90 83 c3 01 <0f> b6 c3 41 3b 44 24 74 0f 83 0b 02 00 00 0f b6 c3 48 8d 14 80 49 RSP: 0018:ffffcb48cbaa39f8 EFLAGS: 00000202 RAX: 0000000000000005 RBX: 00000000137466a1 RCX: 0000000000000000 RDX: ffff89ffc9d851a8 RSI: 0000000000004f0d RDI: 0000000096af0130 RBP: ffffcb48cbaa3a60 R08: 0000000000000000 R09: ffff8a00b7502080 R10: ffff8a00b75ff600 R11: 0000000000000000 R12: ffff89ffc7553870 R13: ffff8a00b7ac8f19 R14: ffff8a00b75020d8 R15: ffff89ffc3d54d80 FS: 0000000000000000(0000) GS:ffff8a014f962000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007558d7f9f4c4 CR3: 0000000178040001 CR4: 00000000001706f0 Call Trace: <TASK> rtw89_hw_scan_prep_chan_list_ax+0x8a/0x400 [rtw89_core] rtw89_hw_scan_start+0x546/0x8a0 [rtw89_core] ? rtw89_fw_h2c_default_cmac_tbl+0x13c/0x1f0 [rtw89_core] rtw89_ops_hw_scan+0xae/0x120 [rtw89_core] drv_hw_scan+0xbb/0x180 [mac80211] __ieee80211_start_scan+0x2fc/0x750 [mac80211] ieee80211_request_scan+0xe/0x20 [mac80211] ieee80211_scan+0x123/0x190 [mac80211] rdev_scan+0x40/0x110 [cfg80211] cfg80211_scan_6ghz+0x5a1/0xa30 [cfg80211] By objdump with source: for (i = 0; i < req->n_6ghz_params; i++) { 5fbc0: 83 c3 01 add $0x1,%ebx --> i++ 5fbc3: 0f b6 c3 movzbl %bl,%eax --> get counter fbc6: 41 3b 44 24 74 cmp 0x74(%r12),%eax * RBX: 00000000137466a1 -> %bl = a1 -> EAX = 000000a1 (161)
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
drivers/net/wireless/realtek/rtw89/fw.c
- What this is
- REALTEK WIRELESS DRIVER (rtw89)MAINTAINERS section matched on drivers/net/wireless/realtek/rtw89/ · linux-wireless@vger.kernel.org · Maintained
- Kernel module
- rtw89_core
Check it on the machine
grep -wE 'CONFIG_RTW89|CONFIG_RTW89_CORE|CONFIG_WLAN|CONFIG_WLAN_VENDOR_REALTEK' /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
lsmod | grep -w rtw89_corePrints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian builds this, but not on every flavour. At least one release below builds the code on some of its kernel flavours and not on others, so the answer depends on the architecture and flavour installed.
- bookwormMnot built on amd64/cloud-amd64, arm64/cloud-arm64
- trixieMnot built on amd64/cloud-amd64, arm64/cloud-arm64, armel/rpi, s390x/s390x
- forky, sidMnot built on amd64/cloud-amd64, arm64/cloud-arm64, s390x/s390x
- M
- a module where it is built at all; some flavours do not build it
- Build switches
- CONFIG_RTW89, CONFIG_RTW89_CORE, CONFIG_WLAN, CONFIG_WLAN_VENDOR_REALTEK
- Reads as
- all on means the file is compiled; any one off means it is not.
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-08-15 (2 months ago)source
- CVSS
- 8.8 high
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- adjacent network (AV:A)source
- EPSS
- 0.40%, higher than 32.5% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- drivers/net
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.4 | 6.6.145 | 966fbed4b446 |
| 6.4 | 6.12.97 | 05d46e303032 |
| 6.4 | 6.18.40 | 7a1ab5fdcae8 |
| 6.4 | 7.1.5 | 140fa699cfd0 |
| 6.4 | 7.2 | 08fdcb529df6 |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:AAttack vector, adjacent network
- The flaw is in the rtw89 WiFi driver scan path; an attacker on the same wireless segment can inject forged RNR/beacon frames to inflate n_6ghz_params above 255, triggering the vulnerable loop during cfg80211 6GHz split-scan processing.
- AC:LAttack complexity, low
- An attacker can reliably flood the BSS cache with 256+ colocated 6GHz AP entries via crafted beacons and wait for routine background or split-scan 6GHz scans on rtw89 hardware; no race or rare configuration outside attacker control is required.
- PR:NPrivileges required, none
- Exploitation requires only transmitting WiFi frames on the victim's RF segment to poison scan inputs; the attacker needs no local account, capability, or namespace privilege on the victim host.
- UI:NUser interaction, none
- The bug fires during automatic kernel/WiFi-stack scanning, including the split-scan 6GHz phase after legacy-band scans; victims need not perform any explicit action beyond normal powered-on operation.
- S:UScope, unchanged
- Impact is kernel soft lockup/panic and potential heap out-of-bounds access within kernel space; it does not cross VM, container, or IOMMU boundaries to another security authority.
- C:HConfidentiality impact, high
- The u8 loop counter truncates at 256 while the index register grows unboundedly, causing out-of-bounds reads of scan_6ghz_params and attacker-influenced channel_idx values used to dereference req->channels[].
- I:HIntegrity impact, high
- The same out-of-bounds indexing drives writes (probe-request skb setup, firmware offload, heap list updates) using corrupted param data, enabling memory corruption beyond simple denial of service.
- A:HAvailability impact, high
- Confirmed kernel soft lockup exceeding 26 seconds in rtw89_hw_scan_add_chan_ax with watchdog-forced panic, rendering the system unavailable until reboot.