CVE-2026-68125 in Linux
Summary
by MITRE • 08/10/2026
In the Linux kernel, the following vulnerability has been resolved:
mac802154: llsec: reject frames shorter than the authentication tag
llsec_do_decrypt_auth() computes the associated-data length for the AEAD request as
assoclen += datalen - authlen;
where datalen is the number of bytes after the MAC header and authlen (4, 8 or 16) is the length of the authentication tag. Nothing verifies that the frame actually carries at least authlen payload bytes. A secured frame whose payload is shorter than the tag makes datalen - authlen negative; assoclen is then passed to aead_request_set_ad() as an unsigned value close to 4 GiB, so crypto_aead_decrypt() walks far off the end of the scatterlist that only spans the real frame.
The frame is fully attacker-controlled and reaches this path from any IEEE 802.15.4 peer in radio range. Reject frames whose payload is shorter than the authentication tag before the subtraction.
Dynamically reproduced on a KASAN kernel as a general-protection-fault in the AEAD scatterwalk, and the fix confirmed.
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Analysis
by VulDB Data Team • 08/10/2026
This vulnerability exists within the Linux kernel's mac802154 subsystem where the llsec module handles link layer security for ieee 802154 wireless networks. The flaw occurs in the llsec_do_decrypt_auth() function which processes authenticated encryption operations using aead (authenticated encryption with associated data) algorithms. When processing secured frames, the code calculates the associated data length by subtracting the authentication tag length from the data payload length without proper validation of frame boundaries. This mathematical operation can result in negative values when the payload is shorter than the authentication tag, leading to severe memory corruption issues.
The technical implementation flaw stems from an unchecked arithmetic operation where datalen - authlen can become negative when frames contain insufficient payload data relative to the authentication tag size. Since assoclen is declared as an unsigned integer, this negative value gets converted to a very large positive number close to 4 gigabytes, causing the crypto_aead_decrypt() function to access memory far beyond the actual frame boundaries. The scatterlist buffer that contains only the real frame data gets traversed past its limits, resulting in general protection faults and potential system crashes or memory corruption.
This vulnerability represents a classic buffer over-read condition that falls under the CWE-129 weakness category for improper validation of array index bounds. The operational impact is significant as it allows remote attackers within radio range to exploit this issue through crafted ieee 802154 frames, potentially leading to system instability, denial of service, or privilege escalation depending on the kernel configuration and memory layout. The attack vector requires only proximity to the affected wireless network, making it particularly concerning for industrial control systems and embedded devices using mac802154 protocols.
The fix implements proper input validation by rejecting frames whose payload is shorter than the authentication tag before performing the arithmetic operation. This approach aligns with defensive programming principles and follows the principle of least privilege by ensuring all inputs are validated before processing. The solution prevents the negative value calculation that leads to memory corruption while maintaining the integrity of legitimate frame processing. This remediation addresses the root cause rather than merely patching symptoms, following security best practices recommended in both nist cyber security framework and iso 27001 standards for secure system design.
The vulnerability demonstrates how cryptographic implementations can introduce subtle but critical flaws when proper boundary checking is omitted during data processing. It highlights the importance of validating all input parameters in crypto operations and underscores the need for comprehensive testing including edge cases such as minimum frame sizes and authentication tag lengths. The fix ensures that the mac802154 subsystem properly validates frame integrity before attempting cryptographic operations, reducing attack surface and improving overall system reliability. This type of vulnerability is particularly relevant in IoT environments where wireless security protocols are extensively used and where memory corruption can lead to complete system compromise through the exploitation of kernel memory management flaws.