CVE-2026-43384
Linux kernel: constant-time MAC check fix in TCP-AO
Is CVE-2026-43384 being exploited?
Not confirmed. CVE-2026-43384 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.46% probability of exploitation in the next 30 days.
How severe is CVE-2026-43384?
CVE-2026-43384 is rated Critical with a CVSS score of 9.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-43384?
Yes. A fix has been recorded for CVE-2026-43384. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-43384 affect?
CVE-2026-43384 affects Linux kernel (net/tcp-ao). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-43384?
Update to patched kernel version
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote timing attack against TCP-AO MAC verification could leak MAC data.
Patch when possible
- affected>= 0a3a809089eb1d4a0a2fd0c16b520d603988c859 and < 8be6ed64966da48b6c4726918f106c18742a5125
- affected>= 0a3a809089eb1d4a0a2fd0c16b520d603988c859 and < a269cbdc442f8658bca35383e34b9d0b0ff95a1c
- affected>= 0a3a809089eb1d4a0a2fd0c16b520d603988c859 and < 080b0e210088296dd50d6637c06c1db14246adfe
- affected>= 0a3a809089eb1d4a0a2fd0c16b520d603988c859 and < 67edfec516d30d3e62925c397be4a1e5185802fc
- affected6.7
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.