{"id":"CVE-2026-63831","title":"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() …","summary":"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() …","severity":"high","cvss":8.8,"cvssVector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","published":"2026-07-19","updated":"2026-08-17","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-63831","references":[{"url":"https://git.kernel.org/stable/c/3a2b378b3a9ca75d3518d879148d2ad25b5714a9","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/7a831bcd0486788283ef35e396d4282ee01bb0d5","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/84a04eb5b210643bd67aab81ff805d32f62aa865","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/86d531337ea1ba02d9f2bc830d07c683d9bfaade","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/993fd674fe85d114e6a8d3963033d4fbbc2170a8","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/bd968bdd568beacfdf98ec537a87527e85f1d0cf","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/e28e7fd34c449028325322a3f5127b92594b7396","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/ff976ef7c39199ebff33c18034636595016db9f0","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-63831.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-63831"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2502243"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-63831"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-63831"},{"url":"https://lore.kernel.org/linux-cve-announce/2026071908-CVE-2026-63831-36ca@gregkh/T"},{"url":"https://access.redhat.com/errata/RHSA-2026:71213"},{"url":"https://access.redhat.com/errata/RHSA-2026:71016"}],"tags":["nvd","csaf","vex","red-hat"],"epss":0.00252,"epssPercentile":0.14945,"ingestedAt":"2026-08-17T05:47:50.444Z","vendor":"Red Hat","product":"Red Hat Enterprise Linux 9","affected":["enterprise_linux 10","enterprise_linux 9","enterprise_linux_baseos_v_8","enterprise_linux_crb_v_8","enterprise_linux_nfv_v_8","enterprise_linux_rt_v_8"],"patched":["enterprise_linux_baseos_v_8","enterprise_linux_crb_v_8","enterprise_linux_nfv_v_8","enterprise_linux_rt_v_8"],"cwe":["CWE-820"],"scores":{"nvd":8.8,"vendor":7},"slug":"CVE-2026-63831","body":"## Overview\n\nIn 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **RHSA-2026:71213** · Red Hat · fixed in: Red Hat Enterprise Linux BaseOS (v. 8), Red Hat Enterprise Linux CRB (v. 8) · released 2026-09-24 · [advisory](https://access.redhat.com/errata/RHSA-2026:71213)\n- **RHSA-2026:71016** · Red Hat · fixed in: Red Hat Enterprise Linux NFV (v. 8), Red Hat Enterprise Linux RT (v. 8) · released 2026-09-23 · [advisory](https://access.redhat.com/errata/RHSA-2026:71016)\n- **Red Hat VEX** · Important · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9 · updated 2026-09-24 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-63831.json)","depth":"twilight","depthScore":48,"depthScoreParts":{"impact":48.4,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}