CVE-2026-98824 in Linux
Summary
by MITRE • 10/18/2026
In the Linux kernel, the following vulnerability has been resolved:
wifi: mac80211: validate TX status rate metadata
minstrel_ht_tx_status() converts the HT/VHT rate reported in a TX status into a group and rate index and uses those to index the minstrel_ht rate tables. The existing validation only checked that an entry was present and had tries recorded; it did not check that the reported MCS, spatial stream count and bandwidth are representable by the tables, so malformed metadata passed to minstrel_ht_get_stats() or minstrel_ht_ri_get_stats() could be used as an out-of-bounds index.
Validate the rate metadata in the common TX status path instead of only in minstrel_ht, since the values are used by more than rate control. The legacy ieee80211_tx_rate array and the rate_info based entries are sanitized in ieee80211_tx_status_ext() and ieee80211_tx_rate_update() before any consumer runs: an entry that does not describe a valid rate for its encoding is dropped. minstrel_ht keeps the checks that depend on its own tables, i.e. the supported number of spatial streams, the MCS group size and the supported bandwidths.
This does not take away the driver's responsibility to report sane values, it only prevents a single bad report from corrupting mac80211 state. No WARN_ON() is added: with panic_on_warn a driver bug would otherwise turn into a denial of service.
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Analysis
by VulDB Data Team • 10/19/2026
The Linux kernel vulnerability identified in the mac80211 wireless subsystem involves an insufficient validation mechanism for transmit status rate metadata within the minstrel_ht rate control algorithm. This flaw allows malformed or maliciously crafted data from network drivers to be processed without adequate bounds checking, potentially leading to out-of-bounds memory access. The core issue resides in the minstrel_ht_tx_status function, which is responsible for converting High Throughput and Very High Throughput rate information reported by hardware into group and rate indices. These indices are subsequently used to look up entries in internal minstrel_ht rate tables that track transmission statistics such as success rates and retry counts. While previous validation logic ensured that an entry existed and had recorded attempts, it failed to verify whether the specific Modulation and Coding Scheme index, spatial stream count, or channel bandwidth reported by the driver were actually representable within the constraints of these internal data structures. Consequently, if a device reports rate metadata with values outside the expected range, the kernel may interpret this as a valid pointer offset, leading to an out-of-bounds read or write operation when accessing the minstrel_ht_get_stats or minstrel_ht_ri_get_stats functions.
From a technical perspective, this vulnerability is classified under CWE-125: Out-of-Bounds Read and CWE-787: Out-of-Bounds Write, depending on how the malformed index interacts with memory layout during runtime execution. The attack vector typically involves an attacker controlling or influencing the wireless driver's behavior, either through physical proximity to a rogue access point sending crafted management frames that trigger specific TX status reports, or by compromising the host system to inject malicious data into the kernel-space network stack. In environments where panic_on_warn is enabled, which converts warning conditions into kernel panics, this vulnerability can be leveraged for Denial of Service attacks. Even without panic_on_warn, repeated exploitation could lead to memory corruption, privilege escalation if adjacent structures are overwritten, or system instability due to corrupted rate control state information that affects subsequent network operations.
The operational impact extends beyond immediate crash scenarios because the mac80211 subsystem relies on accurate TX status data for efficient wireless performance optimization. The minstrel_ht algorithm dynamically adjusts transmission rates based on historical success and failure metrics stored in these tables. If an attacker can corrupt this state by injecting out-of-bounds indices, they may cause the rate control logic to make suboptimal or erroneous decisions regarding packet transmission parameters. This degradation in network performance could be exploited for traffic analysis purposes or as a precursor to more severe exploitation attempts targeting other components of the networking stack that depend on consistent kernel memory integrity. Furthermore, since this validation gap existed specifically within minstrel_ht but not necessarily in all rate control paths initially, it represented an inconsistent security posture where some drivers might inadvertently trigger these checks while others did not, creating unpredictable behavior across different hardware configurations.
To mitigate this vulnerability, the Linux kernel maintainers implemented a comprehensive fix that shifts responsibility for validating TX status metadata to common code paths rather than leaving it solely to individual rate control algorithms. The ieee80211_tx_status_ext and ieee80211_tx_rate_update functions now sanitize legacy ieee80211_tx_rate arrays and rate_info based entries before any consumer, including minstrel_ht, processes them. This ensures that any entry describing an invalid rate for its encoding is dropped early in the processing pipeline, preventing malformed data from reaching sensitive indexing operations. The minstrel_ht algorithm retains specific checks relevant to its internal table constraints, such as verifying supported spatial stream counts and MCS group sizes, but relies on the upstream validation to ensure basic structural validity of the reported metadata. This layered defense approach aligns with security best practices by enforcing input validation at multiple levels within the software architecture.
This remediation strategy reflects adherence to principles outlined in CWE-20: Improper Input Validation, emphasizing that trust boundaries must be strictly enforced even for internal data flows between subsystem components. By centralizing initial sanitization efforts, the kernel reduces the attack surface associated with driver-specific bugs and ensures a consistent baseline of security across all wireless implementations utilizing mac80211. Although drivers remain responsible for reporting sane values as per their hardware specifications, this patch prevents single bad reports from corrupting global mac80211 state, thereby enhancing system resilience against both accidental misconfigurations and deliberate exploitation attempts. The decision to avoid adding WARN_ON statements in critical paths was made specifically to prevent denial of service scenarios triggered by panic_on_warn configurations, demonstrating a careful balance between diagnostic visibility and operational stability. Security practitioners should ensure that systems running affected kernel versions are updated promptly to incorporate these validation improvements, thereby closing the gap that allowed out-of-bounds indexing through wireless TX status metadata.