Medium [CVE-2026-81000] Linux kernel TUN/TAP: Memory corruption due to oversized headroom request
This medium-severity Red Hat Linux advisory covers CVE-2026-81000.
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Summary
A flaw was found in the Linux kernel's TUN/TAP driver. An integer underflow vulnerability exists in the tun_get_user() function when processing oversized headroom requests.
This can occur if Open vSwitch (OVS) propagates an excessively large headroom request to the TUN or TAP device. Successful exploitation could lead to memory corruption, where network packet data is written outside its intended buffer, potentially causing a denial of service or other system instability.
Red Hat severity: Important — CVSS 6.4 (CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H). Weakness: CWE-787.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 54 minutes ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 54 minutes ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 54 minutes ago·verify at source
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