macvlan: inherit needed_headroom and needed_tailroom from lowerdev
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Partial Red Hat: 4 without a fix
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Linux | Linux | 2.6.23 and later | 5.10.271, 5.15.222, 6.1.184, 6.6.153, 6.12.105, 6.18.46, 7.1.10, 7.2 | Patch available | CNA |
- Linux VendorLinux Affected 2.6.23 and later Fixed in 5.10.271, 5.15.222, 6.1.184, 6.6.153, 6.12.105, 6.18.46, 7.1.10, 7.2 Patch available CNA
Remediation
- Fix · CNA Linux (Linux) Fixed in 5.10.271, 5.15.222, 6.1.184, 6.6.153, 6.12.105, 6.18.46, 7.1.10, 7.2
Vendor assessments
Red Hat
Red Hat rating: Important. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet |
| Red Hat Enterprise Linux 7 | Affected | No fix yet |
| Red Hat Enterprise Linux 8 | Affected | No fix yet |
| Red Hat Enterprise Linux 9 | Affected | No fix yet |
Not affected: 1 product
- Red Hat Enterprise Linux 6
Timeline
- 2026-10-02 Threatist record created from CVE-2026-74743
- 2026-10-03 Alias added: GHSA-5qfp-9h7g-rcpm
- 2026-10-03 Fix available: Linux/[email protected], Linux/[email protected], Linux/Linux@7b0eb3e0f363ca79a3af9efd2e87c6258f11da2b +1 · CNA
- 2026-10-03 2 new references · CNA
- 2026-10-13 EPSS moved to the below the 50th percentile
- 2026-10-18 CISA SSVC decision points changed
- 2026-11-05 Affected versions changed · Red Hat
- 2026-11-05 CVSS score changed · Red Hat
References
Other 8
- https://git.kernel.org/stable/c/c2ef3f134b069c54b9cc95cce1a16c38c4939336
- https://git.kernel.org/stable/c/7b0eb3e0f363ca79a3af9efd2e87c6258f11da2b
- https://git.kernel.org/stable/c/8cd90e850e434577bf6774778657d26d6995e53f
- https://git.kernel.org/stable/c/28afc87bd8da0b3348bbbd834c8a89e83712cf5e
- https://git.kernel.org/stable/c/8f6a05dbac05725e0786701eb04778c5bdbe4eaa
- https://git.kernel.org/stable/c/96fa90b74385b7f2b0d97251dd43d5ee6ca44668
- https://git.kernel.org/stable/c/bc9a00fb78e32bccc39d763bfd13a450705bac5d
- https://git.kernel.org/stable/c/cef51860becd9700217c81732ca1eb1ea6ed6fe1
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- TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
- TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4
Sources
- CVE-2026-74743 · CVE Program
- CVE-2026-74743 · NVD
- FIRST EPSS
- GHSA-5qfp-9h7g-rcpm · GitHub Advisory Database · CC BY 4.0
- CVE-2026-74743 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences