CVE-2026-98541: Linux kernel · fou: reject omitted FOU_ATTR_IPPROTO on FOU_ENCAP_DIRECT
Affects Linux kernelSource CVE Database V5
Not known to be exploited · fixed in fd20220f86947d66d4dba2d76f13a28dbd86ef30 : update Linux kernel when convenient.
Data as of 26 Oct 2026, 17:16 UTC
Rated Medium by Threat Radar's AI analysis · CVSS not yet scored by NVD
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 11% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in fd20220f86947d66d4dba2d76f13a28dbd86ef30, d22609f3d13fc5baacd92c222731b03c593401db, b1229b210ef5a39c58be665e6798203751411842 +5
Exploitation evidence
Disclosed: evidence found.
CVE published 18 Oct 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 to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A fix is available and has been applied in the Linux kernel. The patch rejects creation of FOU_ENCAP_DIRECT sockets without the FOU_ATTR_IPPROTO attribute, preventing the memory leak. Users should update to a Linux kernel version that includes the fix identified by the provided commit hashes. No additional mitigation is required.
Description
A vulnerability in the Linux kernel's fou (foo-over-UDP) module allows creation of a FOU_ENCAP_DIRECT socket with an omitted FOU_ATTR_IPPROTO attribute, leading to a memory leak of sk_buff structures. This occurs because the protocol field defaults to zero, causing the UDP tunnel layer to mismanage packet buffers. The issue is fixed by rejecting FOU_ENCAP_DIRECT socket creation when the protocol attribute is missing.
References
- git.kernel.org/stable/c/fd20220f86947d66d4dba2d76f13a28dbd86ef30 (opens in a new tab)
- git.kernel.org/stable/c/46b1ffb7e169c7e401dd890b29e55dbc261f8f01 (opens in a new tab)
- git.kernel.org/stable/c/7f4ba56f5d310dd018972916167985010a5d66a1 (opens in a new tab)
- git.kernel.org/stable/c/3bcc1624cc1cdcc05b566475d6e848093ab2a8f6 (opens in a new tab)
- git.kernel.org/stable/c/8b43f40798bb2758489fbbcae7e841ad4443c213 (opens in a new tab)
- git.kernel.org/stable/c/b1229b210ef5a39c58be665e6798203751411842 (opens in a new tab)
- git.kernel.org/stable/c/520cf06b8ea0ba5bcc1b8b982ef07f02b5e56221 (opens in a new tab)
- git.kernel.org/stable/c/d22609f3d13fc5baacd92c222731b03c593401db (opens in a new tab)