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CVE-2026-64440
staging: rtl8723bs: fix OOB write in HT_caps_handler()
Published 2026-07-25 (3 months ago) by the Linux kernel CNA. Subsystem drivers/staging. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-64440 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-4720-1 · 2026-08-05 · text | 6.1.180-1 | Update the kernel and reboot. DLA-4720-1 shipped the fix on 2026-08-05, in 6.1.180-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.96-1 | Update the kernel and reboot. Fixed in 6.12.96-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.4-1 | Update the kernel and reboot. Fixed in 7.1.4-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.4-1 | Update the kernel and reboot. Fixed in 7.1.4-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4724-1 · 2026-08-07 · text | 6.12.100-1~deb12u1 | Update the kernel and reboot. DLA-4724-1 shipped the fix on 2026-08-07, in 6.12.100-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
HT_caps_handler() iterates pIE->length bytes and writes into HT_caps.u.HT_cap[], which is a fixed 26-byte array (sizeof struct HT_caps_element). Because pIE->length is a raw u8 from an over-the-air 802.11 AssocResponse frame and is never validated, a malicious AP can set it up to 255, causing up to 229 bytes of out-of-bounds writes into adjacent fields of struct mlme_ext_info. Truncate the iteration count to the size of HT_caps.u.HT_cap using umin() so that data from a longer-than-expected IE is silently ignored rather than written out of bounds, preserving interoperability with APs that pad the element. An early return on oversized IEs was considered but rejected: it would bypass the pmlmeinfo->HT_caps_enable = 1 assignment that precedes the loop, silently disabling HT mode for APs that append extra bytes to the HT Capabilities IE.
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/staging/rtl8723bs/core/rtw_wlan_util.c
- What this is
- STAGING SUBSYSTEMMAINTAINERS section matched on drivers/staging/ · linux-staging@lists.linux.dev · Supported
Show whether Debian builds this, per release
Not established. This site could not find the build rule for the affected file in the kernel trees Debian ships, so it has no answer about whether Debian compiles this code. Read that as unknown, never as absent.
- bookworm, trixie, forky, sid, bookworm · linux-6.12?
- ?
- not established - no Makefile entry for the affected file
Where a release above reads "not established", no build rule for the affected file was found in that release's kernel tree. That is a gap in this lookup, not a finding that the code is absent.
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
Signals
- Published
- 2026-07-25 (3 months ago)source
- CVSS
- 8.1 high
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:Hsource recompute it - Attack vector
- adjacent network (AV:A)source
- EPSS
- 0.27%, higher than 17.3% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- drivers/staging
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 4.12 | 5.15.212 | 37f642d47c36 |
| 4.12 | 6.1.178 | 8c872b47c7fc |
| 4.12 | 6.6.145 | bb3b942da412 |
| 4.12 | 6.12.96 | 918537a0fbed |
| 4.12 | 6.18.39 | 6f91621fc450 |
| 4.12 | 7.1.4 | 225b6d3fc7e9 |
| 4.12 | 7.2 | f8001e1a516b |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4724-1 | 2026-08-07 | bookworm 6.12.100-1~deb12u1 | tracker |
| DLA-4723-1 | 2026-08-07 | bullseye 6.1.180-1~deb11u1 | tracker |
| DLA-4720-1 | 2026-08-05 | bookworm 6.1.180-1 | 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
- A nearby attacker can transmit a crafted 802.11 association response over the air; WiFi management-frame injection requires radio proximity and is not routable.
- AC:LAttack complexity, low
- A malicious AP controls the IE length, contents, and handshake timing, making the bit-clearing overwrite deterministic without a race or uncontrollable condition.
- PR:NPrivileges required, none
- The frame is processed before WPA or 802.1X credential verification, and OnAssocRsp does not authenticate its source BSSID; no target privilege or network credential is required.
- UI:NUser interaction, none
- Mobile, embedded, and headless systems commonly associate or roam automatically, allowing an evil-twin AP to reach the handler without human action.
- S:UScope, unchanged
- The corruption affects host-kernel driver state without crossing a VM, IOMMU, sandbox, or other security-authority boundary.
- C:NConfidentiality impact, none
- The primitive only AND-clears following HT and network metadata and cannot reach pointer-bearing fields; no secret-bearing read or attacker-visible disclosure path was found.
- I:HIntegrity impact, high
- The oversized IE causes up to 229 attacker-controlled bit-mask writes beyond the 26-byte array, corrupting live kernel HT information and saved network metadata.
- A:HAvailability impact, high
- The attacker can repeatedly corrupt BSSID, SSID, rate, IE-length, and HT state to prevent association; on a WiFi-dependent controller or IoT device this can sustain total loss of connectivity.