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CVE-2026-52942

netfilter: nf_log: validate MAC header was set before dumping it

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 5.10.261, 5.15.210, 6.1.176, 6.6.143, 6.12.94, and 2 more
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: no
  • Technical impact: partial

Summary

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_log: validate MAC header was set before dumping it The fallback path of dump_mac_header() guards the MAC header access only with "skb->mac_header != skb->network_header", without checking skb_mac_header_was_set(). When the MAC header is unset, mac_header is 0xffff, so the test passes and skb_mac_header(skb) returns skb->head + 0xffff, ~64 KiB past the buffer; the loop then reads dev->hard_header_len bytes out of bounds into the kernel log. This is reachable via the netdev logger: nf_log_unknown_packet() calls dump_mac_header() unconditionally, and an skb sent through AF_PACKET with PACKET_QDISC_BYPASS reaches the egress hook with mac_header still unset (__dev_queue_xmit(), which would reset it, is bypassed). Add the skb_mac_header_was_set() check the ARPHRD_ETHER path already uses, and replace the open-coded MAC header length test with skb_mac_header_len(). Only skbs with an unset MAC header are affected; valid ones are dumped as before. BUG: KASAN: slab-out-of-bounds in dump_mac_header (net/netfilter/nf_log_syslog.c:831) Read of size 1 at addr ffff88800ea49d3f by task exploit/148 Call Trace: kasan_report (mm/kasan/report.c:595) dump_mac_header (net/netfilter/nf_log_syslog.c:831) nf_log_netdev_packet (net/netfilter/nf_log_syslog.c:938 net/netfilter/nf_log_syslog.c:963) nf_log_packet (net/netfilter/nf_log.c:260) nft_log_eval (net/netfilter/nft_log.c:60) nft_do_chain (net/netfilter/nf_tables_core.c:285) nft_do_chain_netdev (net/netfilter/nft_chain_filter.c:307) nf_hook_slow (net/netfilter/core.c:619) nf_hook_direct_egress (net/packet/af_packet.c:257) packet_xmit (net/packet/af_packet.c:280) packet_sendmsg (net/packet/af_packet.c:3114) __sys_sendto (net/socket.c:2265)

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: no · Technical impact: partial

  3. Record last updated

Affected versions

  • Linux Linux

    From 7eb9282cd0efac08b8377cbd5037ba297c77e3f7 · fixed in 2e96e1bc9b4d5450e6c33f078e19a9bc1dda6c0b; From 7eb9282cd0efac08b8377cbd5037ba297c77e3f7 · fixed in d704ee9c7bc68a161684c51a7ac05b446dcf38d4; From 7eb9282cd0efac08b8377cbd5037ba297c77e3f7 · fixed in befb8968a2abdfa948d5600ea7f7a509a292a590; From 7eb9282cd0efac08b8377cbd5037ba297c77e3f7 · fixed in 8a81e336da685423f5b64aac4d571e63d674c52a; From 7eb9282cd0efac08b8377cbd5037ba297c77e3f7 · fixed in c38d41134085193efd5b237cf513ad5b3421a60d; From 7eb9282cd0efac08b8377cbd5037ba297c77e3f7 · fixed in af1b7699466f6556b351fa25d3dc870abfb5d310; From 7eb9282cd0efac08b8377cbd5037ba297c77e3f7 · fixed in 65ef7397eb9a296e91839f5fd10be96f23d332e7; From 7eb9282cd0efac08b8377cbd5037ba297c77e3f7 · fixed in a84b6fedbc97078788be78dbdd7517d143ad1a77

  • Linux Linux

    2.6.36

  • KernelLinux

    From 2.6.36 · fixed in 5.10.261; 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

git.kernel.org