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CVE-2026-74743

Linux

In the Linux kernel, the following vulnerability has been resolved: macvlan: inherit needed_headroom and needed_tailroom from lowerdev macvlan devices inherit hard_header_len from lowerdev during macvlan_init(), but leave needed_headroom and needed_tailroom set to 0. When the underlying lowerdev requires extra headroom or tailroom for headers/trailers (e.g. macsec, ipsec, wireguard, tunnels, or veth with rx headroom), upper layers calculating packet headroom and tailroom fail to reserve sufficient space. This can result in reallocation overhead, skb headroom underflows, or KASAN slab-use-af...

CVSS
9.8
EPSS
-
- percentile
CISA KEV
Not listed
Published
2026.08.27
PRIORITY ASSESSMENT

Review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability-
Technical severityCVSS 9.8

Vulnerability overview

In the Linux kernel, the following vulnerability has been resolved: macvlan: inherit needed_headroom and needed_tailroom from lowerdev macvlan devices inherit hard_header_len from lowerdev during macvlan_init(), but leave needed_headroom and needed_tailroom set to 0. When the underlying lowerdev requires extra headroom or tailroom for headers/trailers (e.g. macsec, ipsec, wireguard, tunnels, or veth with rx headroom), upper layers calculating packet headroom and tailroom fail to reserve sufficient space. This can result in reallocation overhead, skb headroom underflows, or KASAN slab-use-af...

Affected product and versions

Product
Linux
Affected versions
>= b863ceb7ddcea8c55fcf1d7b2ac591d50aa7ed53 < 8cd90e850e434577bf6774778657d26d6995e53f, >= b863ceb7ddcea8c55fcf1d7b2ac591d50aa7ed53 < 28afc87bd8da0b3348bbbd834c8a89e83712cf5e, >= b863ceb7ddcea8c55fcf1d7b2ac591d50aa7ed53 < 8f6a05dbac05725e0786701eb04778c5bdbe4eaa, >= b863ceb7ddcea8c55fcf1d7b2ac591d50aa7ed53 < 96fa90b74385b7f2b0d97251dd43d5ee6ca44668, >= b863ceb7ddcea8c55fcf1d7b2ac591d50aa7ed53 < bc9a00fb78e32bccc39d763bfd13a450705bac5d, >= b863ceb7ddcea8c55fcf1d7b2ac591d50aa7ed53 < cef51860becd9700217c81732ca1eb1ea6ed6fe1, >= 2.6.23
Fixed versions
No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that Linux and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CWE
Not available