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CVE-2026-93806
wifi: cfg80211: validate assoc response length before status and IE access
Published 2026-09-24 (24 days ago) by the Linux kernel CNA. Subsystem net/wireless. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-93806 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 | fixedDLA-4841-1 · 2026-10-17 · text | 6.1.190-1 | Update the kernel and reboot. DLA-4841-1 shipped the fix on 2026-10-17, in 6.1.190-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixedDSA-6528-1 · 2026-09-29 · text | 6.12.111-1 | Update the kernel and reboot. DSA-6528-1 shipped the fix on 2026-09-29, in 6.12.111-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4817-1 · 2026-10-04 · text | 6.12.111-1~deb12u1 | Update the kernel and reboot. DLA-4817-1 shipped the fix on 2026-10-04, in 6.12.111-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
cfg80211_rx_assoc_resp() initialises the status and response-IE fields of cfg80211_connect_resp_params from the management frame before proving that the frame is long enough for those offsets. S1G and regular association responses also have different IE offsets, but the S1G path only patched resp_ie after the unsafe initialiser had already run. Defer resp_ie, resp_ie_len, and status to after the link-iteration loop. Use a bool to remember whether the frame is S1G, then validate the appropriate minimum length and set all three fields in a single if/else block. Funnel short-frame and SME-reject cleanup through a shared free_bss label for the abandon paths.
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.
net/wireless/mlme.c
- What this is
- 802.11 (including CFG80211/NL80211)MAINTAINERS section matched on net/wireless/ · linux-wireless@vger.kernel.org · Maintained
- Kernel module
- cfg80211
Check it on the machine
grep -wE 'CONFIG_CFG80211|CONFIG_WIRELESS' /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 cfg80211Prints 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
- trixie, forky, sidMnot built on amd64/cloud-amd64, arm64/cloud-arm64, s390x/s390x
- bookworm · linux-6.12Mnot built on amd64/cloud-amd64, arm64/cloud-arm64
- M
- a module where it is built at all; some flavours do not build it
- Build switches
- CONFIG_CFG80211, CONFIG_WIRELESS
- 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
- 2026-09-24 (24 days 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
- 0.25%, higher than 15.8% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- net/wireless
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 2.6.32 | 6.1.189 | 3bcaaaa4ad33 |
| 2.6.32 | 6.6.158 | 71be658246c9 |
| 2.6.32 | 6.12.111 | a57310600c1e |
| 2.6.32 | 6.18.53 | 78ac450ad462 |
| 2.6.32 | 7.2 | b760113aeca2 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4841-1 | 2026-10-17 | bookworm 6.1.190-1 | tracker |
| DLA-4817-1 | 2026-10-04 | bookworm 6.12.111-1~deb12u1 | tracker |
| DSA-6528-1 | 2026-09-29 | trixie 6.12.111-1 | tracker |
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 malformed input is an 802.11 (Re)Association Response in data->buf that cfg80211_rx_assoc_resp() parses as ieee80211_mgmt. It is delivered by ieee80211_rx_h_mgmt → ieee80211_sta_rx_queued_frame → ieee80211_rx_mgmt_assoc_resp, or by mwifiex_ret_802_11_associate → mwifiex_process_assoc_resp. Those frames are WiFi radio-range, not a routable IP protocol.
- AC:LAttack complexity, low
- mwifiex_ret_802_11_associate copies resp->params of length (resp->size - S_DS_GEN) into assoc_rsp_buf with no 30-byte floor; mwifiex_process_assoc_resp then calls cfg80211_rx_assoc_resp with that len. A rogue AP's truncated AssocResp makes data->len < offsetof(ieee80211_mgmt, u.assoc_resp.variable), so the size_t subtraction for cr.resp_ie_len wraps every time. No race.
- PR:NPrivileges required, none
- cfg80211_rx_assoc_resp runs on the station MLME RX path. ieee80211_rx_mgmt_assoc_resp only requires ifmgd->assoc_data and matching SA/BSSID; mwifiex_host_mlme_work_queue has no capable() or uid check. The AssocResp is parsed before the 4-way handshake, so a radio attacker needs no host account or PSK.
- UI:NUser interaction, none
- A saved-network auto-reconnect or evil-twin of a known SSID puts ifmgd->assoc_data / the mwifiex associate command in flight; the attacker's AssocResp is then handled in ieee80211_rx_mgmt_assoc_resp or mwifiex_process_assoc_resp with no further victim click.
- S:UScope, unchanged
- The underflowed cr.resp_ie_len is consumed in nl80211_send_connect_result() → nla_put(NL80211_ATTR_RESP_IE) / __nla_put() on host-kernel heap (the nlmsg skb and adjacent objects). No VM, IOMMU, or sandbox boundary is crossed.
- C:HConfidentiality impact, high
- When data->len < 30, cr.resp_ie_len = data->len - offsetof(ieee80211_mgmt, u.assoc_resp.variable) wraps. nl80211_send_connect_result() then nla_put(NL80211_ATTR_RESP_IE, that length, cr.resp_ie) and __nla_put memcpy's from mgmt->u.assoc_resp.variable, disclosing kernel memory far past the short frame; status_code at offset 26 is also an OOB load.
- I:HIntegrity impact, high
- nlmsg_new(100 + cr->resp_ie_len + ...) in nl80211_send_connect_result wraps the skb allocation small when resp_ie_len underflows. nla_put then passes that length as int into __nla_put, whose memcpy writes past the skb, and __nla_reserve memset's at the wrapped u16 nla_len — a kernel heap overflow write.
- A:HAvailability impact, high
- The same __nla_put memcpy of the wrapped cr.resp_ie_len, or __nla_reserve's memset at the wrapped u16 nla_len, can walk into unmapped or redzone memory and oops/panic. Repeating association retriggers it.