CVE-2026-98276net: lock the socket in sock_gettstamp()

Description

In the Linux kernel, the following vulnerability has been resolved: net: lock the socket in sock_gettstamp() sk->sk_flags must only be changed while holding the socket lock, because sock_set_flag() and sock_reset_flag() use non atomic operations (__set_bit() and __clear_bit()). sock_gettstamp() is one of the last places where a bit of sk->sk_flags is changed from a syscall without owning the socket lock, through sock_enable_timestamp(sk, SOCK_TIMESTAMP). sk_set_memalloc() and sk_clear_memalloc() also change sk->sk_flags without the socket lock, but their callers (nbd, iscsi_tcp, nvme-tcp, sunrpc, wireguard) need a careful audit, this will be addressed in a separate patch. Jungwoo Lee and Wongi Lee reported an UDP socket use-after-free caused by this bug: a SIOCGSTAMPNS_NEW ioctl racing with bind() can cancel the SOCK_RCU_FREE bit that udp_lib_get_port() just set, because both threads perform a read-modify-write on the same word. CPU 0 (bind) CPU 1 (SIOCGSTAMPNS_NEW) -------------------------------- ---------------------------- read sk_flags = F read sk_flags = F compute F | BIT(SOCK_RCU_FREE) compute F | BIT(SOCK_TIMESTAMP) store F | BIT(SOCK_RCU_FREE) sk_add_node_rcu(sk, ...) store F | BIT(SOCK_TIMESTAMP) After the lost update, SOCK_RCU_FREE is clear while the socket is visible to lockless UDP receive lookups. sk_destruct() then frees the socket immediately instead of waiting for a RCU grace period, while the receive path still holds a reference-less pointer to it: BUG: KASAN: slab-use-after-free in ipv4_pktinfo_prepare+0x30/0x410 Read of size 8 at addr ffff888008806610 by task exploit/207 CPU: 0 UID: 1000 PID: 207 Comm: exploit Not tainted 6.12.95+ #1 ipv4_pktinfo_prepare+0x30/0x410 udp_queue_rcv_one_skb+0x51c/0x1180 udp_unicast_rcv_skb+0x109/0x350 ip_protocol_deliver_rcu+0x14b/0x310 ip_local_deliver_finish+0x29d/0x390 ip_local_deliver+0x24d/0x2a0 Only grab the socket lock when SOCK_TIMESTAMP has to be set, to keep the common case lockless.

Timeline

Scores

EPSS (exploitation in 30 days)

0.13% · top 98% of all CVEs (13 Nov 2026)

The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.8.

Affected products

• Linux · Linux

  • affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 – < 18899e2e4023369a8f7739c2255a59a9748d8d17
  • affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 – < 88c804847dd87dc613b771b392ccecdb94725032
  • affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 – < 3b12d3967e96f1b7b977d9fc352ae29a1b299a82
  • affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 – < 17b2a1eb97fdb2a2cbaeab3b146b26797ea9311f
  • affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 – < 1f73253add8365d0dad0a4f421acaa8c21d20cef
  • affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 – < d9f96bc2d822501f84d1caa6275a2c6b316ca2c4
  • affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 – < 899650bbf985b7bfd2a7b808357df9b16e6d6959
  • affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 – < 9ed55f3dbef4f4adfe65eb03b0c35c53229a8490

• Linux · Linux

  • affected 2.6.12
  • unaffected < 2.6.12
  • unaffected 5.10.271 – ≤ 5.10.*
  • unaffected 5.15.222 – ≤ 5.15.*
  • unaffected 6.1.189 – ≤ 6.1.*
  • unaffected 6.6.158 – ≤ 6.6.*
  • unaffected 6.12.112 – ≤ 6.12.*
  • unaffected 6.18.54 – ≤ 6.18.*
  • unaffected 7.2.8 – ≤ 7.2.*
  • unaffected 7.3 – ≤ *

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• EUVD EUVD-2026-93204 (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2026-98276](https://cveledger.app/badge/CVE-2026-98276.svg)](https://cveledger.app/cve/CVE-2026-98276)

Record last updated 19 Oct 2026, 09:16 UTC.