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CVE-2026-72019

HIGH 7.3

Published 2026-08-15 · Last modified 2026-08-19

In the Linux kernel, the following vulnerability has been resolved: macsec: don't read an unset MAC header in macsec_encrypt() macsec_encrypt() reads the Ethernet header via eth_hdr(skb) (skb->head + skb->mac_header) to memmove() the 12 source/destination MAC bytes forward and make room for the SecTAG. On the AF_PACKET SOCK_RAW + PACKET_QDISC_BYPASS transmit path the skb reaches the macsec ndo_start_xmit() with the MAC header unset, so eth_hdr(skb) resolves to skb->head + (u16)~0 and the read is out of bounds: a 12-byte heap over-read that is also emitted on the wire as the frame's outer source/destination MAC. KASAN reports a slab-out-of-bounds read in macsec_start_xmit() on 6.0; on current mainline a CONFIG_DEBUG_NET build flags it as an unset mac header in skb_mac_header(). On the TX path the L2 header is at skb->data, so use skb_eth_hdr(), added by commit 96cc4b69581d ("macvlan: do not assume mac_header is set in macvlan_broadcast()") for exactly this purpose.

ELEVATED IMPACT

Severe if exploited (CVSS 7.3), but no known exploitation and low modeled probability. Patch on a normal cadence.

Exploitation likelihood

0.2%chance of exploitation in 30 days · 6th percentile

○ In CISA KEV ○ Public exploit / PoC

Impact if exploited

7.3CVSS 3.1 · HIGH

  • ConfidentialityHigh
  • IntegrityLow
  • AvailabilityHigh

What an attacker needs

  • ⚠Access: Requires local access to the host
  • ⚠Privileges: Requires a low-privilege account
  • ✓User interaction: No user interaction needed
  • ✓Complexity: No special conditions — reliably repeatable

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept & exploit code

Test against your own equipment

curl -s https://vulnpedia.com/cve/CVE-2026-72019/poc.jsonMachine-readable PoC index for this CVE (for automation).

Listed for defensive triage, patch verification, and authorized testing on systems you own. Machine-readable: /cve/CVE-2026-72019/poc.json

Affected

Vendors Linux

Products Linux

Weakness (CWE)

Not classified.

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H

All CVSS metrics

  • HIGH 7.3 v3.1 · CNA Primary
    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H
  • HIGH 7.3 v3.1 · NVD Secondary
    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H

References

Technical & other

Sources: NVD · CVE.org · EPSS