OS Kernel CVE: ZeroMask ffs() in iwlwifi BA Session -> OOB Access
CVE-2026-64255 Published on July 24, 2026
wifi: iwlwifi: mld: validate sta_mask before ffs() in BA session handlers
In the Linux kernel, the following vulnerability has been resolved:
wifi: iwlwifi: mld: validate sta_mask before ffs() in BA session handlers
Three BA session handlers use ffs(ba_data->sta_mask) - 1 to derive a
station ID without checking that sta_mask is non-zero. When sta_mask is
zero, ffs() returns 0 and the subtraction wraps to 0xFFFFFFFF, causing
an out-of-bounds access on fw_id_to_link_sta[].
Add WARN_ON_ONCE(!ba_data->sta_mask) guards before each ffs() call,
consistent with the existing check in iwl_mld_ampdu_rx_start().
Products Associated with CVE-2026-64255
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Affected Versions
Linux:- Version 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and below 1de92789ce31e46fa7e7d8e89c90b19cdb1c103b is affected.
- Version 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and below fe7f339f63c9dc4ca546ed7ac38ba4bb3a99dcfc is affected.
- Version 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and below f056fc2b927448d37eca6b6cacc3d1b0f67b20d2 is affected.
- Before 6.18.38 is affected.
- Before 7.1.3 is affected.
- Version 6.18.38, <= 6.18.* is unaffected.
- Version 7.1.3, <= 7.1.* is unaffected.
- Version 7.2-rc1, <= * is unaffected.