CVE-2026-98503packet: use ubuf_info completion for TX_RING packets

Description

In the Linux kernel, the following vulnerability has been resolved: packet: use ubuf_info completion for TX_RING packets tpacket_snd sends skbs with frags pointing into its ring slots. Slots are released when skb->destructor is called. A call to skb_orphan calls skb->destructor before the skb is freed. This can cause the slot to be reused while still linked into the skb. Switch to standard zerocopy completion (ubuf_info) so the slot is only released once all references to the payload are freed or copied. Restore skb->destructor to standard sock_wfree. The ubuf_info completion callback can be called with a NULL skb, but only from net_zcopy_put and related API, used by zerocopy implementations that hold their own reference on the uarg, such as MSG_ZEROCOPY. This uarg is only ever completed from skb_zcopy_clear, so skb is always set. To prevent userspace from aliasing in-flight state on shared ring slots, allocate tpacket_uarg per packet, rather than per slot. This adds a small allocation to the transmit path. Use standard kmalloc to allow backporting to stable kernels. The uarg holds an sk_wmem_alloc reference, rather than an sk_refcnt reference. packet_free_tx_ring waits on sk_wmem_alloc before freeing the ring pages. Always allocate vec->deferred for tx_ring so page-backed rings also wait on sk_wmem_alloc when skb_copy_ubufs drops page refs before calling tpacket_ubuf_complete. Drop the tx_ring.pg_vec test that tpacket_destruct_skb performed before accessing the slot. The sk_wmem_alloc reference now guarantees that the slot is valid. The test is also not sufficient by itself, as it reads pg_vec without pg_vec_lock, so it can race with packet_set_ring. As a result a slot is released when its payload is copied, which can be before transmission (e.g., in skb_orphan_frags_rx). If copied before skb_tx_timestamp() is called, no slot timestamp is recorded, similar to when skb_orphan() was called early in the datapath before this patch. Revert the now unused previous skb_zcopy_.._nouarg infra. Depends on commit 992cc9f94ca9 ("net/packet: defer vmalloc TX_RING free until skbs finish").

Timeline

Scores

No CVSS score yet: neither the CNA, CISA nor NVD has scored this CVE. NVD status: Received.

EPSS (exploitation in 30 days)

0.20% · top 90% of all CVEs (12 Nov 2026)

The list uses the assigner's score when there is one, then CISA's, then NVD's: Not scored.

Affected products

• Linux · Linux

  • affected 5cd8d46ea1562be80063f53c7c6a5f40224de623 – < e67c455d79fbf709a94965f09a2be6bf4f4ba5fd
  • affected 5cd8d46ea1562be80063f53c7c6a5f40224de623 – < eda9bcb721f15a93746a99eabda33d80b86404fd
  • affected 5cd8d46ea1562be80063f53c7c6a5f40224de623 – < 2a0c9afefc0ecea2cc30ccfbbbc98182a0986191
  • affected 5cd8d46ea1562be80063f53c7c6a5f40224de623 – < 9518405613863d0bf0700927a21367f5942cf058
  • affected 67f6fba765ef8cb19089d476e3c367212a2fbdfd
  • affected f2a67e68dbaeae7c88e5522873d7b908911f9f77
  • affected 4.14.86 – < 4.15
  • affected 4.19.7 – < 4.20

• Linux · Linux

  • affected 4.20
  • unaffected < 4.20
  • unaffected 6.12.112 – ≤ 6.12.*
  • unaffected 6.18.55 – ≤ 6.18.*
  • unaffected 7.2.9 – ≤ 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-2026-103743 (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-2026-98503](https://cveledger.app/badge/CVE-2026-98503.svg)](https://cveledger.app/cve/CVE-2026-98503)

Record last updated 19 Oct 2026, 09:20 UTC.