CVE-2026-74668: Linux kernel · packet: use consistent hard_header_len in TX_RING send path
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 7.8 High.
Data as of 26 Oct 2026, 12:55 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 2% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 22 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A fix for this vulnerability has been implemented in the Linux kernel by snapshotting hard_header_len consistently during packet processing. Users should apply the official kernel updates that include this fix. Since no vendor advisory or patch links are provided here, check the Linux kernel official repositories or your distribution's security advisories for the relevant patch. No additional mitigation is indicated.
Description
In the Linux kernel, the following vulnerability has been resolved: packet: use consistent hard_header_len in TX_RING send path tpacket_snd() reads dev->hard_header_len independently for skb allocation and header construction in tpacket_fill_skb(). Concurrent netdevice reconfiguration can therefore make the reserved headroom smaller than the amount later pushed, or make copylen - hard_header_len negative. Snapshot hard_header_len once before processing ring frames and use it for the frame limit, headroom allocation, copy length, and skb construction. Pass the snapshot to tpacket_fill_skb(). The separate SOCK_DGRAM consistency problem between hard_header_len and header_ops->create is not addressed here.
References
- nvd.nist.gov/vuln/detail/CVE-2026-74668 (opens in a new tab)
- git.kernel.org/stable/c/016763e829cac37b3234eace86fd0a4c560de4a7 (opens in a new tab)
- git.kernel.org/stable/c/21b5953e7494c16a42e6cd8cf110e18d13ae4a6b (opens in a new tab)
- git.kernel.org/stable/c/27e068d1b35dbec10a3cf268887c94407be4badc (opens in a new tab)
- git.kernel.org/stable/c/d48ea5c9c4c34dc0df621f0e39ed3a16b644621a (opens in a new tab)
- git.kernel.org/stable/c/d85d2fd54e901637c81d847811e03c662aee13cd (opens in a new tab)
- ubuntu.com/security/CVE-2026-74668 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-74668 (opens in a new tab)
- git.kernel.org/stable/c/2a73b2c37ee3060a880b53cd24783d93fc7be5f8 (opens in a new tab)
- git.kernel.org/stable/c/e79f59a8527a49078cfaf8fe8fb5fcefc20c76d2 (opens in a new tab)
- git.kernel.org/stable/c/9c7e8ff48c377bef18c3d178748aea0575b69ede (opens in a new tab)