In the Linux kernel, the following vulnerability has been resolved: macvlan: inherit needed_headroom and needed_tailroom from lowerdev …
CVE-2026-74743 · published 26 Aug 2026
How serious is it
- Severity: critical, CVSS score 9.8 out of 10.
- No exploit prediction (EPSS) score yet.
- Not on the CISA list of exploited vulnerabilities.
- No public exploit in Exploit-DB.
Is your app affected by CVE-2026-74743?
Paste this prompt into Claude Code, Cursor or any AI coding tool: it runs a free Shippable scan of your project and fixes what it finds. Built with Lovable, Bolt or v0? Scan your live app. Or upload your package file.
Who is affected
- Linux Linux: 2.6.23
How to check
- Find out whether you run the affected product and which version, then compare it with the versions above.
How to fix
Copies a prompt for Claude Code, Cursor or Codex that asks it to check whether you run this product.
- Apply the vendor's update or mitigation from the references below. If there is none yet, limit exposure of the affected service until there is.
- If a vulnerable version was live, check your logs and rotate the secrets that server could read.
The advisory
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.
Check your whole app
Dependencies are only half of it. Free and read-only: before you push, run npx shippable-dev scan localhost:3000 in your project folder, no account needed. For your live app, you prove it's yours with a one-line tag first.
References
- git.kernel.org/stable/c/28afc87bd8da0b3348bbbd834c8a89e83712cf5e
- git.kernel.org/stable/c/7b0eb3e0f363ca79a3af9efd2e87c6258f11da2b
- git.kernel.org/stable/c/8cd90e850e434577bf6774778657d26d6995e53f
- git.kernel.org/stable/c/8f6a05dbac05725e0786701eb04778c5bdbe4eaa
- git.kernel.org/stable/c/96fa90b74385b7f2b0d97251dd43d5ee6ca44668
- git.kernel.org/stable/c/bc9a00fb78e32bccc39d763bfd13a450705bac5d
- git.kernel.org/stable/c/c2ef3f134b069c54b9cc95cce1a16c38c4939336
- git.kernel.org/stable/c/cef51860becd9700217c81732ca1eb1ea6ed6fe1
Merged from NVD. Last updated 24 Oct 2026. All vulnerabilities · RSS · JSON