{"id":"CVE-2026-63831","summary":"mac802154: llsec: add skb_cow_data() before in-place crypto","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nmac802154: llsec: add skb_cow_data() before in-place crypto\n\nllsec_do_encrypt_unauth(), llsec_do_encrypt_auth(),\nllsec_do_decrypt_unauth(), and llsec_do_decrypt_auth() all perform\nin-place cryptographic transformations on skb data.  They build a\nscatterlist with sg_init_one() pointing into the skb's linear data area\nand then pass the same scatterlist as both src and dst to the crypto API\n(e.g. crypto_skcipher_encrypt/decrypt, crypto_aead_encrypt/decrypt).\n\nOn the RX path, __ieee802154_rx_handle_packet() clones the received skb\nbefore handing it to each subscriber via ieee802154_subif_frame().  The\ncloned skb shares the same underlying data buffer via reference\ncounting.  When llsec_do_decrypt() subsequently modifies this shared\nbuffer in place, it corrupts data that other clones -- potentially\nbelonging to other sockets or subsystems -- still reference.\n\nOn the TX path, similar data sharing can occur when an skb's head has\nbeen cloned (skb_cloned() returns true).\n\nThe fix is to call skb_cow_data() before performing any in-place crypto\noperation.  skb_cow_data() ensures that the skb's data area is not\nshared: if the skb head is cloned or the data spans multiple fragments,\nit copies the data into a private buffer that can be safely modified in\nplace.  This is the same pattern used by:\n\n  - ESP (net/ipv4/esp4.c, net/ipv6/esp6.c)\n  - MACsec (drivers/net/macsec.c)\n  - WireGuard (drivers/net/wireguard/receive.c)\n  - TIPC (net/tipc/crypto.c)\n\nWithout this guard, in-place crypto on shared skb data leads to:\n  - Silent data corruption of other skb clones\n  - Use-after-free when the crypto API scatterwalk writes through a\n    page that has already been freed by another clone's kfree_skb()\n  - Kernel crashes under concurrent 802.15.4 traffic with security\n    enabled (KASAN/KMSAN reports slab-use-after-free)\n\nFound by 0sec (https://0sec.ai) using automated source analysis.","modified":"2026-07-22T05:30:06.233842470Z","published":"2026-07-19T12:02:24.320Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63831.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/3a2b378b3a9ca75d3518d879148d2ad25b5714a9"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7a831bcd0486788283ef35e396d4282ee01bb0d5"},{"type":"WEB","url":"https://git.kernel.org/stable/c/84a04eb5b210643bd67aab81ff805d32f62aa865"},{"type":"WEB","url":"https://git.kernel.org/stable/c/86d531337ea1ba02d9f2bc830d07c683d9bfaade"},{"type":"WEB","url":"https://git.kernel.org/stable/c/993fd674fe85d114e6a8d3963033d4fbbc2170a8"},{"type":"WEB","url":"https://git.kernel.org/stable/c/bd968bdd568beacfdf98ec537a87527e85f1d0cf"},{"type":"WEB","url":"https://git.kernel.org/stable/c/e28e7fd34c449028325322a3f5127b92594b7396"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ff976ef7c39199ebff33c18034636595016db9f0"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63831.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-63831"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"03556e4d0dbbbf4af9df76f4a3839c86f6afb015"},{"fixed":"3a2b378b3a9ca75d3518d879148d2ad25b5714a9"},{"fixed":"7a831bcd0486788283ef35e396d4282ee01bb0d5"},{"fixed":"ff976ef7c39199ebff33c18034636595016db9f0"},{"fixed":"e28e7fd34c449028325322a3f5127b92594b7396"},{"fixed":"993fd674fe85d114e6a8d3963033d4fbbc2170a8"},{"fixed":"bd968bdd568beacfdf98ec537a87527e85f1d0cf"},{"fixed":"86d531337ea1ba02d9f2bc830d07c683d9bfaade"},{"fixed":"84a04eb5b210643bd67aab81ff805d32f62aa865"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-63831.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.16.0"},{"fixed":"5.10.260"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.211"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.177"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.144"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.95"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.38"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.3"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-63831.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"}]}