Core infrastructure flaw; kernel-level, impacts Linux kernel/libceph and Ceph deployments; could cause RCE and outages across many environments.
CVE-2026-43407
Linux kernel libceph: out-of-bounds in ceph_handle_auth_reply may mem-corrupt.
Is CVE-2026-43407 being exploited?
Not confirmed. CVE-2026-43407 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 0.54% probability of exploitation in the next 30 days.
How severe is CVE-2026-43407?
CVE-2026-43407 is rated Critical with a CVSS score of 9.1. 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-2026-43407?
Yes. A fix has been recorded for CVE-2026-43407. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-43407 affect?
CVE-2026-43407 affects Linux kernel, Ceph deployments. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-43407?
Patch now; update kernel and Ceph lib, reboot if required
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Kernel memory corruption via crafted Ceph AUTH_REPLY; potential remote code execution.
Immediate action required
- affected>= 4e7a5dcd1bbab6560fbc8ada29a840e7a20ed7bc and < ea080b21092590122c3f971cf588932cdbf47847
- affected>= 4e7a5dcd1bbab6560fbc8ada29a840e7a20ed7bc and < edc678e5cd11730a2834b43071d8923f05bc334d
- affected>= 4e7a5dcd1bbab6560fbc8ada29a840e7a20ed7bc and < 6cee34d6669fe176b4259131adb1a145c939b472
- affected>= 4e7a5dcd1bbab6560fbc8ada29a840e7a20ed7bc and < 8bb87547e92dcf0928ed763c60e0ac8d733c3656
- affected>= 4e7a5dcd1bbab6560fbc8ada29a840e7a20ed7bc and < ed024d2f4c79c0eb2464df0fb640610ac301f9a0
- affected>= 4e7a5dcd1bbab6560fbc8ada29a840e7a20ed7bc and < f9da5c1bbac5c8e33259fe00ed7347438fffa969
- affected>= 4e7a5dcd1bbab6560fbc8ada29a840e7a20ed7bc and < 9f9e2297f45fc2d2524eb104c289d69ddef95665
- affected>= 4e7a5dcd1bbab6560fbc8ada29a840e7a20ed7bc and < b282c43ed156ae15ea76748fc15cd5c39dc9ab72
- affected2.6.34
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.