GHSA-3745-G9HM-6M5F
Vulnerability from github – Published: 2026-07-19 12:30 – Updated: 2026-07-20 15:31In 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.
{
"affected": [],
"aliases": [
"CVE-2026-63831"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-07-19T12:16:56Z",
"severity": "HIGH"
},
"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\u0027s 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\u0027s 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\u0027s 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\u0027s 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.",
"id": "GHSA-3745-g9hm-6m5f",
"modified": "2026-07-20T15:31:47Z",
"published": "2026-07-19T12:30:24Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-63831"
},
{
"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"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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