CVE-2026-63831: Linux kernel · mac802154: llsec: add skb_cow_data() before in-place crypto
Affects Linux kernelSource CVE Database V5
Not known to be exploited · CVSS 8.8 High · fixed in ff976ef7c39199ebff33c18034636595016db9f0 : patch Linux kernel soon.
Data as of 26 Oct 2026, 13:47 UTC
- EPSS
- 0.3% chance of exploitation in 30 days – higher than 23% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers cannot reliably automate steps 1–4 of the kill chain
- Technical impact
- Total control over the software or total information disclosure
CISA SSVC assessment, 2026-10-16.
- Patch
- Available – fixed in ff976ef7c39199ebff33c18034636595016db9f0, e28e7fd34c449028325322a3f5127b92594b7396, bd968bdd568beacfdf98ec537a87527e85f1d0cf +5
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 19 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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Description
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.
References
- git.kernel.org/stable/c/3a2b378b3a9ca75d3518d879148d2ad25b5714a9 (opens in a new tab)
- git.kernel.org/stable/c/7a831bcd0486788283ef35e396d4282ee01bb0d5 (opens in a new tab)
- git.kernel.org/stable/c/ff976ef7c39199ebff33c18034636595016db9f0 (opens in a new tab)
- git.kernel.org/stable/c/e28e7fd34c449028325322a3f5127b92594b7396 (opens in a new tab)
- git.kernel.org/stable/c/993fd674fe85d114e6a8d3963033d4fbbc2170a8 (opens in a new tab)
- git.kernel.org/stable/c/bd968bdd568beacfdf98ec537a87527e85f1d0cf (opens in a new tab)
- git.kernel.org/stable/c/86d531337ea1ba02d9f2bc830d07c683d9bfaade (opens in a new tab)
- git.kernel.org/stable/c/84a04eb5b210643bd67aab81ff805d32f62aa865 (opens in a new tab)