UBUNTU-CVE-2026-90018: Buffer Overflow
In the Linux kernel, the following vulnerability has been resolved: staging: rtl8723bs: fix OOB read / stack overflow in rtwgetwpsattr() rtwgetwpsattr() walks WPS attributes inside a WPS IE taken from a wireless management frame. For each candidate attribute it only checks that the fixed 4-byte attribute header (2-byte ID + 2-byte length) fits inside the IE: if (attrptr + 4 > wpsie + wpsielen) break; u16 attrid = getunalignedbe16(attrptr); u16 attrdatalen = getunalignedbe16(attrptr + 2); u16 attrlen = attrdatalen + 4; attrdatalen (and therefore attrlen) is read directly from the wire and is never checked against the remaining bytes in the IE before being used as the size of: memcpy(bufattr, attrptr, attrlen); Since attrlen is fully attacker controlled (0 to 65535+4), this is both a heap OOB read of wpsie, and, more seriously, a stack buffer overflow at several call sites where bufattr is a single-byte stack variable, e.g. rtwgetwpsattrcontent()'s callers passing WPSATTRSELECTEDREGISTRAR into a stack "u8 sr"/"u8 selectedregistrar" (drivers/staging/rtl8723bs/osdep/ioctlcfg80211.c, drivers/staging/rtl8723bs/core/rtwmlmeext.c). A crafted WPS IE in a beacon or probe response processed during scanning can therefore smash the stack of the parsing thread. rtwgetwpsattrcontent() itself has no independent length check and simply trusts the attrlen it gets back from rtwgetwpsattr(), so fixing the bound here also fixes that caller. The "attrptr + 4 > wpsie + wpsielen" header check above was added by commit 1463ca3ec6601 ("staging: rtl8723bs: fix OOB reads in rtwgetsecie(), rtwgetwapiie(), and rtwgetwpsattr()"), which bounded the fixed header but never extended the check to cover the variable-length attribute data that follows it. Add that missing check before attrlen is used as a memcpy() length or accepted as a match.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
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ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1 - Compensating control
In rtw_get_wps_attr(), add a bounds check ensuring the variable-length attribute data (attr_data_len, and therefore attr_len) fits within the remaining bytes of the WPS IE before using attr_len as a memcpy() length or accepting it as a match.
Event History
Frequently Asked Questions
Who is realistically exposed to this issue?
Systems using the rtl8723bs staging wireless driver are exposed when they process WPS information elements from wireless management frames. The attack vector is adjacent, so an attacker must be within wireless range rather than able to attack solely over the Internet.
What does an attacker need to exploit it?
An attacker can send a crafted wireless management frame containing a malformed WPS information element. The supplied vector indicates no privileges or user interaction are required.
What is the potential impact?
The malformed attribute length can cause an out-of-bounds read and overflow stack buffers at affected call sites. The reported severity vector indicates potential high impact to confidentiality, integrity, and availability.