# CVE-2026-90018: staging: rtl8723bs: fix OOB read / stack overflow in rtw_get_wps_attr()

> A crafted WPS IE in a wireless frame causes a stack buffer overflow in the rtl8723bs driver, allowing remote code execution or system crash.

- **Severity:** High 8.8 (`CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 16 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-101678, BELL-CVE-2026-90018, DEBIAN-CVE-2026-90018, GHSA-jrhx-3qq6-x5q2, UBUNTU-CVE-2026-90018

## What is CVE-2026-90018?

CVE-2026-90018 is a high-severity memory corruption vulnerability in Linux, published on 16 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

staging: rtl8723bs: fix OOB read / stack overflow in rtw_get_wps_attr()

rtw_get_wps_attr() 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 (attr_ptr + 4 > wps_ie + wps_ielen)
		break;
	u16 attr_id = get_unaligned_be16(attr_ptr);
	u16 attr_data_len = get_unaligned_be16(attr_ptr + 2);
	u16 attr_len = attr_data_len + 4;

attr_data_len (and therefore attr_len) 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(buf_attr, attr_ptr, attr_len);

Since attr_len is fully attacker controlled (0 to 65535+4), this is
both a heap OOB read of wps_ie, and, more seriously, a stack buffer
overflow at several call sites where buf_attr is a single-byte
stack variable, e.g. rtw_get_wps_attr_content()'s callers passing
WPS_ATTR_SELECTED_REGISTRAR into a stack "u8 sr"/"u8
selected_registrar" (drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c,
drivers/staging/rtl8723bs/core/rtw_mlme_ext.c). A crafted WPS IE in a
beacon or probe response processed during scanning can therefore
smash the stack of the parsing thread.

rtw_get_wps_attr_content() itself has no independent length check
and simply trusts the attr_len it gets back from rtw_get_wps_attr(),
so fixing the bound here also fixes that caller.

The "attr_ptr + 4 > wps_ie + wps_ielen" header check above was added
by commit 1463ca3ec6601 ("staging: rtl8723bs: fix OOB reads in
rtw_get_sec_ie(), rtw_get_wapi_ie(), and rtw_get_wps_attr()"), 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 attr_len is used as a memcpy() length or accepted as a
match.

## Which versions are affected by CVE-2026-90018?


## How do I fix CVE-2026-90018?

Apply the vendor's patch.

## Is CVE-2026-90018 being exploited?

There is no known exploitation of CVE-2026-90018 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90018 and fix it if it is affected.

What it is: CVE-2026-90018 is a high-severity memory corruption vulnerability in Linux, published on 16 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-90018 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-90018/ (Markdown: https://insights.sbomify.com/CVE-2026-90018/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90018
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90018
- OSV: https://osv.dev/vulnerability/CVE-2026-90018

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90018/
Summaries are generated and may contain mistakes; the official description above is the record.