netfilter: nft_exthdr: fix register tracking for F_PRESENT flag

Summary

In the Linux kernel, the following vulnerability has been resolved: netfilter: nft_exthdr: fix register tracking for F_PRESENT flag nft_exthdr_init() passes user-controlled priv->len to nft_parse_register_store(), which marks that many bytes in the register bitmap as initialized. However, when NFT_EXTHDR_F_PRESENT is set, the eval paths write only 1 byte (nft_reg_store8) or 4 bytes (*dest = 0 on TCP/DCCP error path). When len > 4, registers beyond the first are never written, retaining uninitialized stack data from nft_regs. Bail out if userspace requests too much data when F_PRESENT is set.

Timeline

1. Jun 25, 2026, 8:39 AM UTCCVE published
2. Oct 15, 2026, 1:22 AM UTCRecord last updated

Affected versions

• Linux Linux

  From c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783 · fixed in 8738b1b6d0e639ca1fc0f61516afd3557ac4ecc6; From c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783 · fixed in 19748967d59c31d24d21d40b728570788310b237; From c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783 · fixed in 46fc15a044e9938e7ea77786fb37edd2cd74f031; From c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783 · fixed in cd513e43b4b2bd1de39e2367bc4261c699a8652f; From c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783 · fixed in 67b27434c43b68a97becda98c9f0c8cf6cba2134; From c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783 · fixed in 78069a6d8bc86c9e036eb82c2af4a19cc1871a53; From c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783 · fixed in f08fb3d42fd3aad0b7a263da3ac3ebaf0845e265; From c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783 · fixed in 772cecf198da732faebb5dcfc46d66a505be8495

• Linux Linux

  4.11

• KernelLinux

  From 4.11.0 · fixed in 5.10.259; From 5.11.0 · fixed in 5.15.210; From 5.16.0 · fixed in 6.1.176; From 6.2.0 · fixed in 6.6.143; From 6.7.0 · fixed in 6.12.94; From 6.13.0 · fixed in 6.18.36; From 6.19.0 · fixed in 7.0.13

References 8