Linux vulnerability

What happened

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.

Affected versions

Linux: c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783 through before 8738b1b6d0e639ca1fc0f61516afd3557ac4ecc6 (git); c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783 through before 19748967d59c31d24d21d40b728570788310b237 (git); c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783 through before 46fc15a044e9938e7ea77786fb37edd2cd74f031 (git); c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783 through before cd513e43b4b2bd1de39e2367bc4261c699a8652f (git); c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783 through before 67b27434c43b68a97becda98c9f0c8cf6cba2134 (git); c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783 through before 78069a6d8bc86c9e036eb82c2af4a19cc1871a53 (git); c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783 through before f08fb3d42fd3aad0b7a263da3ac3ebaf0845e265 (git); c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783 through before 772cecf198da732faebb5dcfc46d66a505be8495 (git); 4.11; V3.1.6 through before * (custom) Fixed: See vendor advisory.

Why it matters

Review the vendor advisory and exposure of the affected product to determine operational impact.

Detection & mitigation

• Apply vendor-provided updates or mitigations.
• Review affected product exposure and access logs.