--- id: CVE-2026-63831 title: |- 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() … summary: |- 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() … 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' - url: 'https://access.redhat.com/errata/RHSA-2026:88687' - url: 'https://access.redhat.com/errata/RHSA-2026:71233' - url: 'https://access.redhat.com/errata/RHSA-2026:71232' tags: - nvd - csaf - vex - red-hat - cve.org epss: 0.00307 epssPercentile: 0.23663 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 cna: 8.8 ssvc: exploitation: none automatable: 'no' technicalImpact: total timestamp: '2026-10-16T15:31:21.214861Z' --- ## Overview 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. ## Remediation Refer to the linked advisories for vendor-supplied fixes and affected version ranges. ## Vendor advisories - **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) - **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) - **Red Hat VEX** · Important · affected: Red Hat Enterprise Linux 9 · no fix planned: Red Hat Enterprise Linux 9 · updated 2026-10-23 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-63831.json) - **RHSA-2026:88687** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream EUS (v. 10.0), Red Hat Enterprise Linux BaseOS EUS (v. 10.0), Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0), Red Hat Enterprise Linux Real Time for NFV EUS (v. 10.0), Red Hat Enterprise Linux Real Time EUS (v. 10.0) · released 2026-10-23 · [advisory](https://access.redhat.com/errata/RHSA-2026:88687) - **RHSA-2026:71233** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux BaseOS (v. 10), Red Hat Enterprise Linux CodeReady Linux Builder (v. 10), Red Hat Enterprise Linux Real Time for NFV (v. 10), Red Hat Enterprise Linux Real Time (v. 10) · released 2026-09-24 · [advisory](https://access.redhat.com/errata/RHSA-2026:71233) - **RHSA-2026:71232** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux BaseOS (v. 9), Red Hat Enterprise Linux CodeReady Linux Builder (v. 9), Red Hat Enterprise Linux Real Time for NFV (v. 9), Red Hat Enterprise Linux Real Time (v. 9) · released 2026-09-24 · [advisory](https://access.redhat.com/errata/RHSA-2026:71232)