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CVE-2026-74649
staging: rtl8723bs: fix missing shared-key auth challenge length check
Published 2026-08-22 (2 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-2026-74649 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-4777-1 · 2026-09-08 · text | 6.1.187-1 | Update the kernel and reboot. DLA-4777-1 shipped the fix on 2026-09-08, in 6.1.187-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixedDSA-6466-1 · 2026-08-25 · text | 6.12.105-1 | Update the kernel and reboot. DSA-6466-1 shipped the fix on 2026-08-25, in 6.12.105-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.9-1 | Update the kernel and reboot. Fixed in 7.1.9-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.9-1 | Update the kernel and reboot. Fixed in 7.1.9-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4788-1 · 2026-09-19 · text | 6.12.107-1~deb12u1 | Update the kernel and reboot. DLA-4788-1 shipped the fix on 2026-09-19, in 6.12.107-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
The WEP shared-key authentication handler uses the challenge-text element's attacker-controlled length without checking it against the fixed 128-byte chg_txt buffer. In OnAuthClient() the length from rtw_get_ie() - up to 255 - is used to perform memcpy() into the 128-byte pmlmeinfo->chg_txt, so a malicious AP sending a malformed WLAN_EID_CHALLENGE element can overflow/underfill chg_txt by up to 127 bytes. It is reachable over the air, before association, during shared-key authentication. In the case of an overflow, the driver can write out of bounds. In the case of an underfill, the driver can echo stale buffer memory. The challenge text is defined to be exactly 128 octets, which is already provided as the WLAN_AUTH_CHALLENGE_LEN define; require the element to be exactly that length before use.
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_mlme_ext.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
- 2026-08-22 (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
- 0.29%, higher than 20.0% 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 | 5.15.216 | 39ae10330710 |
| 4.12 | 6.1.183 | 4d018e7d7d90 |
| 4.12 | 6.6.152 | 4ba402fd4700 |
| 4.12 | 6.12.104 | 87c2f073d2aa |
| 4.12 | 6.18.45 | a28a4b0592e4 |
| 4.12 | 7.1.9 | 6235b5156b48 |
| 4.12 | 7.2 | 2c56ef658ac8 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4788-1 | 2026-09-19 | bookworm 6.12.107-1~deb12u1 | tracker |
| DLA-4777-1 | 2026-09-08 | bookworm 6.1.187-1 | tracker |
| DSA-6466-1 | 2026-08-25 | trixie 6.12.105-1 | 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 malicious AP on the same WiFi radio segment sends a crafted 802.11 authentication management frame; rtl8723bs receives it from the air via SDIO and dispatches it through mgt_dispatcher() to OnAuthClient() before association completes.
- AC:LAttack complexity, low
- The rogue AP fully controls the malformed auth seq-2 response and its timing; once the client enters WEP shared-key authentication the attacker can reliably supply any challenge IE length up to 255 without races or conditions outside attacker control.
- PR:NPrivileges required, none
- Exploitation requires no privileges on the victim host; a nearby attacker operating a malicious AP triggers the pre-association shared-key authentication handler without authenticating to the client or needing local shell or capability access.
- UI:NUser interaction, none
- No fresh victim interaction is needed at exploit time; evil-twin APs can invoke auto-connect to saved WEP profiles, and auth-algorithm auto-fallback from failed open auth can reach shared-key auth without a new user action during the attack.
- S:UScope, unchanged
- The overflow corrupts driver-private mlme_ext_info fields within the kernel WiFi driver context; impact remains within kernel/driver authority and does not cross a VM, container, or IOMMU security boundary.
- C:HConfidentiality impact, high
- Underfill leaves stale data in the 128-byte chg_txt buffer that issue_auth() later transmits back to the attacker in auth seq 3, disclosing prior kernel memory; overflow also enables memory corruption paths that can yield further information disclosure.
- I:HIntegrity impact, high
- memcpy() uses attacker-controlled len (up to 255) into the fixed 128-byte chg_txt array, writing up to 127 bytes past the buffer into adjacent mlme_ext_info fields (aid, capability, HT/WMM structs, network IEs), enabling exploitable kernel memory corruption.
- A:HAvailability impact, high
- Out-of-bounds writes into critical mlme_ext_info state in kernel context can corrupt driver data structures and trigger kernel oops, panic, or hang, causing complete loss of availability on affected embedded/mobile devices using this driver.