macvlan: inherit needed_headroom and needed_tailroom from lowerdev

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-74743
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-26 15:16:53 UTC
Updated2026-08-27 06:17:24 UTC
DescriptionIn 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-after-free crashes when dev_hard_header() / macvlan_hard_header() prepends header data or when lower devices append tailroom. Fix this by: 1. Inheriting needed_headroom and needed_tailroom from lowerdev in macvlan_init(). 2. Propagating needed_headroom and needed_tailroom updates to attached macvlans in macvlan_device_event() when receiving NETDEV_FEAT_CHANGE events.

Risk And Classification

Primary CVSS: v3.1 9.8 CRITICAL from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

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

EPSS: 0.005190000 probability, percentile 0.419190000 (date 2026-08-27)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected b863ceb7ddcea8c55fcf1d7b2ac591d50aa7ed53 8cd90e850e434577bf6774778657d26d6995e53f git Not specified
CNA Linux Linux affected b863ceb7ddcea8c55fcf1d7b2ac591d50aa7ed53 28afc87bd8da0b3348bbbd834c8a89e83712cf5e git Not specified
CNA Linux Linux affected b863ceb7ddcea8c55fcf1d7b2ac591d50aa7ed53 8f6a05dbac05725e0786701eb04778c5bdbe4eaa git Not specified
CNA Linux Linux affected b863ceb7ddcea8c55fcf1d7b2ac591d50aa7ed53 96fa90b74385b7f2b0d97251dd43d5ee6ca44668 git Not specified
CNA Linux Linux affected b863ceb7ddcea8c55fcf1d7b2ac591d50aa7ed53 bc9a00fb78e32bccc39d763bfd13a450705bac5d git Not specified
CNA Linux Linux affected b863ceb7ddcea8c55fcf1d7b2ac591d50aa7ed53 cef51860becd9700217c81732ca1eb1ea6ed6fe1 git Not specified
CNA Linux Linux affected 2.6.23 Not specified
CNA Linux Linux unaffected 2.6.23 semver Not specified
CNA Linux Linux unaffected 6.1.184 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.153 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.105 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.46 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.10 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/cef51860becd9700217c81732ca1eb1ea6ed6fe1 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/28afc87bd8da0b3348bbbd834c8a89e83712cf5e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/8f6a05dbac05725e0786701eb04778c5bdbe4eaa 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/96fa90b74385b7f2b0d97251dd43d5ee6ca44668 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/8cd90e850e434577bf6774778657d26d6995e53f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/bc9a00fb78e32bccc39d763bfd13a450705bac5d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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