Critical RCE in Linux kernel via libceph key handling; widespread kernel exposure.
CVE-2026-43304
RCE in Linux kernel libceph key handling due to CEPH_MAX_KEY_LEN length check.
Is CVE-2026-43304 being exploited?
Not confirmed. CVE-2026-43304 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 0.50% probability of exploitation in the next 30 days.
How severe is CVE-2026-43304?
CVE-2026-43304 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-2026-43304?
Yes. A fix has been recorded for CVE-2026-43304. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-43304 affect?
CVE-2026-43304 affects Linux kernel (libceph). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-43304?
Apply kernel update with fix; verify libceph key handling.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote code execution via crafted key material; kernel-level access and potential full host compromise.
Patch when possible
- affected>= cd1a677cad994021b19665ed476aea63f5d54f31 and < 6405e8c680974bb74e2c98d5249fb52c7b12a6c6
- affected>= cd1a677cad994021b19665ed476aea63f5d54f31 and < 8d745d38c88ecbed95f6b2b39857bf89f35a3244
- affected>= cd1a677cad994021b19665ed476aea63f5d54f31 and < e1dc45d97975f9db65694d234fbddf1915176e16
- affected>= cd1a677cad994021b19665ed476aea63f5d54f31 and < 1b275bd49e58752efb83767a5d1aed41356c5e64
- affected>= cd1a677cad994021b19665ed476aea63f5d54f31 and < c1a0f5f1e5e7e98c36a362ec3d1fcfd9932931ed
- affected>= cd1a677cad994021b19665ed476aea63f5d54f31 and < d82467c07b03a27c3c5469b62bb3b726305a80bb
- affected>= cd1a677cad994021b19665ed476aea63f5d54f31 and < ac431d597a9bdfc2ba6b314813f29a6ef2b4a3bf
- affected5.11
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.