CVE-2026-74496: Linux kernel · fou: Fix use-after-free in fou_create()
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 7.8 High : upgrade to 6.8.0-1036.39 soon.
Data as of 26 Oct 2026, 17:16 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.
- Patch
- Available – fixed in 6.8.0-1036.39
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 15 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
Upgrade the Ubuntu linux-nvidia-tegra package to 6.8.0-1036.39.
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.
Description
In the Linux kernel, the following vulnerability has been resolved: fou: Fix use-after-free in fou_create() fou_create() publishes struct fou through sk_user_data before adding the new FOU port to the per-netns list. If fou_add_to_port_list() fails, the error path frees fou while it is still reachable through sk_user_data. A concurrent receive can then dereference the freed object in fou_from_sock(). This ordering issue was previously noted in the linked discussion. The failure is reachable when local port 0 is requested. Each socket binds to a different ephemeral port, but fou_cfg_cmp() compares the requested port 0 and reports -EALREADY once an entry already exists. Release the tunnel socket before freeing fou so sk_user_data is cleared first, and defer reclamation with kfree_rcu() to protect concurrent RCU readers. This matches the lifetime handling in fou_release().
References
- ubuntu.com/security/CVE-2026-74496 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-74496 (opens in a new tab)
- git.kernel.org/linus/b14361aca6350ff7907b0e9903c7b94dc7d5d4a0 (opens in a new tab)
- git.kernel.org/stable/c/a28d8903bfe76089ea4bbdbff9976965f9ef8107 (opens in a new tab)
- git.kernel.org/stable/c/b14361aca6350ff7907b0e9903c7b94dc7d5d4a0 (opens in a new tab)
- nvd.nist.gov/vuln/detail/CVE-2026-74496 (opens in a new tab)
- git.kernel.org/stable/c/0ee628a58d83e571f36ec9f07624d6845e420c50 (opens in a new tab)
- git.kernel.org/stable/c/58835985c035a8333742f829ad7e0889a082f9d3 (opens in a new tab)
- git.kernel.org/stable/c/9042867d4701728f0c6527215b11471759904d8f (opens in a new tab)
- git.kernel.org/stable/c/99f4d3120b244f92e5df787152041296a2860cb5 (opens in a new tab)
- git.kernel.org/stable/c/a6fca682cfa2041e31aa72cc397c4a1406eb7468 (opens in a new tab)
- git.kernel.org/stable/c/b3f9c3e60aa25453774f899d25b5e61dd0bec1d5 (opens in a new tab)
- ubuntu.com/security/notices/USN-8886-1 (opens in a new tab)