Linux Kernel NULL Ptr Deref in mac80211 mesh_rx_csa_frame()
CVE-2026-23279 Published on March 25, 2026
wifi: mac80211: fix NULL pointer dereference in mesh_rx_csa_frame()
In the Linux kernel, the following vulnerability has been resolved:
wifi: mac80211: fix NULL pointer dereference in mesh_rx_csa_frame()
In mesh_rx_csa_frame(), elems->mesh_chansw_params_ie is dereferenced
at lines 1638 and 1642 without a prior NULL check:
ifmsh->chsw_ttl = elems->mesh_chansw_params_ie->mesh_ttl;
...
pre_value = le16_to_cpu(elems->mesh_chansw_params_ie->mesh_pre_value);
The mesh_matches_local() check above only validates the Mesh ID,
Mesh Configuration, and Supported Rates IEs. It does not verify the
presence of the Mesh Channel Switch Parameters IE (element ID 118).
When a received CSA action frame omits that IE, ieee802_11_parse_elems()
leaves elems->mesh_chansw_params_ie as NULL, and the unconditional
dereference causes a kernel NULL pointer dereference.
A remote mesh peer with an established peer link (PLINK_ESTAB) can
trigger this by sending a crafted SPECTRUM_MGMT/CHL_SWITCH action frame
that includes a matching Mesh ID and Mesh Configuration IE but omits the
Mesh Channel Switch Parameters IE. No authentication beyond the default
open mesh peering is required.
Crash confirmed on kernel 6.17.0-5-generic via mac80211_hwsim:
BUG: kernel NULL pointer dereference, address: 0000000000000000
Oops: Oops: 0000 [#1] SMP NOPTI
RIP: 0010:ieee80211_mesh_rx_queued_mgmt+0x143/0x2a0 [mac80211]
CR2: 0000000000000000
Fix by adding a NULL check for mesh_chansw_params_ie after
mesh_matches_local() returns, consistent with how other optional IEs
are guarded throughout the mesh code.
The bug has been present since v3.13 (released 2014-01-19).
Products Associated with CVE-2026-23279
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Affected Versions
Linux:- Version 8f2535b92d685c68db4bc699dd78462a646f6ef9 and below 2b5f282b1b7241ef624c3399a1cdff0bb1a3eeab is affected.
- Version 8f2535b92d685c68db4bc699dd78462a646f6ef9 and below 22a9adea7e26d236406edc0ea00b54351dd56b9c is affected.
- Version 8f2535b92d685c68db4bc699dd78462a646f6ef9 and below f5d8af683410a8c82e48b51291915bd612523d9a is affected.
- Version 8f2535b92d685c68db4bc699dd78462a646f6ef9 and below cc6d5a3c0a854aeae00915fc5386570c86029c60 is affected.
- Version 8f2535b92d685c68db4bc699dd78462a646f6ef9 and below be8b82c567fda86f2cbb43b7208825125bb31421 is affected.
- Version 8f2535b92d685c68db4bc699dd78462a646f6ef9 and below 017c1792525064a723971f0216e6ef86a8c7af11 is affected.
- Version 3.13 is affected.
- Before 3.13 is unaffected.
- Version 6.1.167, <= 6.1.* is unaffected.
- Version 6.6.130, <= 6.6.* is unaffected.
- Version 6.12.77, <= 6.12.* is unaffected.
- Version 6.18.17, <= 6.18.* is unaffected.
- Version 6.19.7, <= 6.19.* is unaffected.
- Version 7.0-rc2, <= * is unaffected.
Exploit Probability
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