Missing Synchronization Affecting kernel-rt-modules package, versions *


Severity

Recommended
0.0
high
0
10

Based on CentOS security rating.

Threat Intelligence

EPSS
0.24% (16th percentile)

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  • Snyk IDSNYK-CENTOS10-KERNELRTMODULES-18558043
  • published6 Aug 2026
  • disclosed19 Jul 2026

Introduced: 19 Jul 2026

NewCVE-2026-63831  (opens in a new tab)
CWE-820  (opens in a new tab)

How to fix?

There is no fixed version for Centos:10 kernel-rt-modules.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-rt-modules package and not the kernel-rt-modules package as distributed by Centos. See How to fix? for Centos:10 relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1