CVE-2026-63831
Received Received - Intake

Heap Overflow in Linux Kernel mac802154 LLSEC

Publication date: 2026-07-19

Last updated on: 2026-07-19

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: mac802154: llsec: add skb_cow_data() before in-place crypto llsec_do_encrypt_unauth(), llsec_do_encrypt_auth(), llsec_do_decrypt_unauth(), and llsec_do_decrypt_auth() all perform in-place cryptographic transformations on skb data. They build a scatterlist with sg_init_one() pointing into the skb's linear data area and then pass the same scatterlist as both src and dst to the crypto API (e.g. crypto_skcipher_encrypt/decrypt, crypto_aead_encrypt/decrypt). On the RX path, __ieee802154_rx_handle_packet() clones the received skb before handing it to each subscriber via ieee802154_subif_frame(). The cloned skb shares the same underlying data buffer via reference counting. When llsec_do_decrypt() subsequently modifies this shared buffer in place, it corrupts data that other clones -- potentially belonging to other sockets or subsystems -- still reference. On the TX path, similar data sharing can occur when an skb's head has been cloned (skb_cloned() returns true). The fix is to call skb_cow_data() before performing any in-place crypto operation. skb_cow_data() ensures that the skb's data area is not shared: if the skb head is cloned or the data spans multiple fragments, it copies the data into a private buffer that can be safely modified in place. This is the same pattern used by: - ESP (net/ipv4/esp4.c, net/ipv6/esp6.c) - MACsec (drivers/net/macsec.c) - WireGuard (drivers/net/wireguard/receive.c) - TIPC (net/tipc/crypto.c) Without this guard, in-place crypto on shared skb data leads to: - Silent data corruption of other skb clones - Use-after-free when the crypto API scatterwalk writes through a page that has already been freed by another clone's kfree_skb() - Kernel crashes under concurrent 802.15.4 traffic with security enabled (KASAN/KMSAN reports slab-use-after-free) Found by 0sec (https://0sec.ai) using automated source analysis.

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Meta Information

Published
2026-07-19
Last Modified
2026-07-19
Generated
2026-07-20
AI Q&A
2026-07-19
EPSS Evaluated
N/A
NVD
CVE-2026-63831
EUVD
EUVD-2026-45497

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves in-place cryptographic operations on shared skb data buffers in the mac802154 llsec subsystem. Functions like llsec_do_encrypt_unauth() and llsec_do_decrypt_auth() modify skb data directly without ensuring the buffer is private. This can corrupt data shared with other sockets or subsystems and lead to kernel crashes or use-after-free errors.

Detection Guidance

This vulnerability is specific to the Linux kernel's mac802154 subsystem and involves in-place cryptographic operations on shared skb data buffers. Detection requires kernel source code analysis or runtime checks for kernel crashes, slab-use-after-free errors, or data corruption in 802.15.4 traffic with security enabled. No direct commands are provided in the context to detect this issue.

Impact Analysis

This vulnerability can cause silent data corruption, kernel crashes, or use-after-free errors when using IEEE 802.15.4 wireless communication with security enabled. It may affect systems running affected Linux kernel versions by disrupting network traffic or causing system instability.

Compliance Impact

This vulnerability primarily affects data integrity and security in Linux kernel networking, which could indirectly impact compliance with standards like GDPR or HIPAA by enabling data corruption or unauthorized access through cryptographic failures in 802.15.4 wireless communication.

Mitigation Strategies

Apply the kernel patch that adds skb_cow_data() before in-place crypto operations in mac802154. Update to a kernel version that includes this fix. Monitor for kernel crashes or data corruption in 802.15.4 traffic with security enabled.

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