High [CVE-2026-52942] validate MAC header was set before dumping it
This high-severity Red Hat Linux advisory covers CVE-2026-52942 affecting Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat Enterprise Linux 10.
Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.
VulniPulse record published Record updated
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.
Affected products named by the advisory: Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9; Red Hat Enterprise Linux 10; Red Hat package: kernel-rt.
Is CVE-2026-52942 exploited?
No exploitation is reported in the sources VulniPulse tracks: CVE-2026-52942 is not in the CISA KEV catalog (checked ) and this advisory does not report exploitation. That is not proof the vulnerability cannot be exploited.
How do I fix CVE-2026-52942?
Upgrade to a fixed release named by Red Hat:
- kernel-rt-0:4.18.0-553.162.1.rt7.503.el8_10
- kernel-0:4.18.0-553.162.1.el8_10
- kernel-0:5.14.0-687.55.1.el9_8
- RHSA-2026:66324
- RHSA-2026:66325
- RHSA-2026:76739
Confirm against the vendor advisory before you patch.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative. Check it before change work.
Official advisory · high-confidence parse· fetched 13 days ago·verify at source
- kernel-rt-0:4.18.0-553.162.1.rt7.503.el8_10
- kernel-0:4.18.0-553.162.1.el8_10
- kernel-0:5.14.0-687.55.1.el9_8
- RHSA-2026:66324
- RHSA-2026:66325
- RHSA-2026:76739
Official advisory · high-confidence parse· fetched 13 days ago·verify at source
Mitigation
Upgrade to a fixed release: kernel-rt-0:4.18.0-553.162.1.rt7.503.el8_10, kernel-0:4.18.0-553.162.1.el8_10, kernel-0:5.14.0-687.55.1.el9_8, RHSA-2026:66324, RHSA-2026:66325, RHSA-2026:76739. That is the remediation for this advisory.
The vendor advisory may list interim mitigations or workarounds not captured here. Review it before change work.
Official advisory · high-confidence parse· fetched 13 days ago·verify at source
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