CVE-2026-64174: wifi: cfg80211: advance loop vars in cfg80211_merge_profile()

From: Greg Kroah-Hartman <[email protected]>

Description
===========

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

wifi: cfg80211: advance loop vars in cfg80211_merge_profile()

cfg80211_merge_profile() reassembles a Multi-BSSID non-transmitted BSS
profile that has been split across multiple consecutive MBSSID elements.
Its while-loop calls

	cfg80211_get_profile_continuation(ie, ielen, mbssid_elem, sub_elem)

but never advances mbssid_elem or sub_elem inside the body.  Each
iteration therefore searches for a continuation that follows the same
fixed pair; the helper returns the same next_mbssid; and the same
next_sub bytes are memcpy()'d into merged_ie at a growing offset until
the buffer fills.

Advance both mbssid_elem and sub_elem to the just-consumed continuation
so the next call to cfg80211_get_profile_continuation() searches for a
further continuation beyond it (or returns NULL when none exists).

A specially-crafted malicious beacon can take advantage of this bug
to cause the kernel to spend an excessive amount of time in
cfg80211_merge_profile (up to as much as 2ms per beacon received),
which could theoretically be abused in some way.

The Linux kernel CVE team has assigned CVE-2026-64174 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 5.2 with commit fe806e4992c9047affd263bcc13b2c047029a726 and fixed in 5.10.258 with commit 5817e1e5205498a5df66eba2b34e817f4210fd0f
	Issue introduced in 5.2 with commit fe806e4992c9047affd263bcc13b2c047029a726 and fixed in 5.15.209 with commit cedbb608494ba1e7a5c6c56b7f1d3fd470094f28
	Issue introduced in 5.2 with commit fe806e4992c9047affd263bcc13b2c047029a726 and fixed in 6.1.175 with commit c0bc4c8bd556cbe036a5b9ed333c0aab9aadfcb8
	Issue introduced in 5.2 with commit fe806e4992c9047affd263bcc13b2c047029a726 and fixed in 6.6.142 with commit 1ced0f5a851f9cae274545a42a06c459b7fd8881
	Issue introduced in 5.2 with commit fe806e4992c9047affd263bcc13b2c047029a726 and fixed in 6.12.92 with commit 67915715fd3874057457363c87c63e18829527df
	Issue introduced in 5.2 with commit fe806e4992c9047affd263bcc13b2c047029a726 and fixed in 6.18.34 with commit 6cfae4914439878b8acb35c7e3b40096eeb2ad9c
	Issue introduced in 5.2 with commit fe806e4992c9047affd263bcc13b2c047029a726 and fixed in 7.0.11 with commit 1343a480f84b80c1249133a90ef87f8751d65cbb
	Issue introduced in 5.2 with commit fe806e4992c9047affd263bcc13b2c047029a726 and fixed in 7.1 with commit 7666dbb1bacc4ba522b96740cba7283d243d16e1

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-64174
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	net/wireless/scan.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/5817e1e5205498a5df66eba2b34e817f4210fd0f
	https://git.kernel.org/stable/c/cedbb608494ba1e7a5c6c56b7f1d3fd470094f28
	https://git.kernel.org/stable/c/c0bc4c8bd556cbe036a5b9ed333c0aab9aadfcb8
	https://git.kernel.org/stable/c/1ced0f5a851f9cae274545a42a06c459b7fd8881
	https://git.kernel.org/stable/c/67915715fd3874057457363c87c63e18829527df
	https://git.kernel.org/stable/c/6cfae4914439878b8acb35c7e3b40096eeb2ad9c
	https://git.kernel.org/stable/c/1343a480f84b80c1249133a90ef87f8751d65cbb
	https://git.kernel.org/stable/c/7666dbb1bacc4ba522b96740cba7283d243d16e1