{"cve":"CVE-2026-63831","nvd":{"published":"2026-07-19T12:16:56.460","modified":"2026-10-22T19:24:19.030","status":"Analyzed","description":"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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":8.8},"cwes":["CWE-416"],"references":["https://git.kernel.org/stable/c/3a2b378b3a9ca75d3518d879148d2ad25b5714a9","https://git.kernel.org/stable/c/7a831bcd0486788283ef35e396d4282ee01bb0d5","https://git.kernel.org/stable/c/84a04eb5b210643bd67aab81ff805d32f62aa865","https://git.kernel.org/stable/c/86d531337ea1ba02d9f2bc830d07c683d9bfaade","https://git.kernel.org/stable/c/993fd674fe85d114e6a8d3963033d4fbbc2170a8"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-23T16:39:26.291718493+00:00"},"epss":{"cve":"CVE-2026-63831","score":0.00307,"percentile":0.23304,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}