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Alpaquita LinuxStreamSecurity Advisory
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CVE-2026-74743

Published: August 29, 2026Last modified: August 29, 2026

Description

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-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.

Severity score breakdown

ParameterValue
Base score9.8
Attack VectorNETWORK
Attack complexityLOW
Privileges requiredNONE
User interactionNONE
ScopeUNCHANGED
ConfidentialityHIGH
Integrity impactHIGH
Availability impactHIGH
VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Status

ProductReleasePackageStatus
Alpaquita Linux23 LTSlinux-ltsVulnerable (6.1.182-r0)
25 LTSlinux-ltsVulnerable (6.12.103-r0)
Streamlinux-ltsFixed (6.18.46-r0)

References

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