Linux KernelOperating system · Linux
CVE-2026-43304
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedIn the Linux kernel, the following vulnerability has been resolved: libceph: define and enforce CEPH_MAX_KEY_LEN When decoding the key, verify that the key material would fit into a fixed-size buffer in process_auth_done() and generally has a sane length. The new CEPH_MAX_KEY_LEN check replaces the existing check for a key with no key material which is a) not universal since CEPH_CRYPTO_NONE has to be excluded and b) doesn't provide much value since a smaller than needed key is just as invalid as no key -- this has to be handled elsewhere anyway.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceA buffer validation vulnerability exists in libceph's process_auth_done() function where key material length is not properly validated against a fixed-size buffer. Without enforcing CEPH_MAX_KEY_LEN, a malformed or truncated key can be accepted, potentially leading to buffer overflow or memory corruption during authentication.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
Linux KernelOperating system
>= 5.11, < 5.15.202>= 5.16, < 6.1.165>= 6.2, < 6.6.128>= 6.7, < 6.12.75>= 6.13, < 6.18.16>= 6.19, < 6.19.6CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Verify Ceph is in useCheck if the libceph module is loaded or if Ceph packages (libceph, ceph-common, cephfs) are installed. Commands: `lsmod | grep ceph`, `dpkg -l | grep ceph`, or `rpm -qa | grep ceph`Affected if Ceph libraries or kernel modules are present on the system
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Confirm kernel versionRun `uname -r` or `cat /proc/version` to obtain the running kernel version. Compare against the affected ranges: >= 5.11, < 5.15.202; >= 5.16, < 6.1.165; >= 6.2, < 6.6.128; >= 6.7, < 6.12.75; >= 6.13, < 6.18.16; >= 6.19, < 6.19.6Affected if The kernel version falls within any of the listed vulnerable ranges
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Check Ceph authentication is enabledExamine Ceph configuration files (typically in /etc/ceph/ or /etc/cephfs/) for auth entries, or inspect running Ceph services (ceph-mon, ceph-osd, ceph-mds) via `ps aux | grep ceph`. Look for auth_cluster_required or auth_client_required settingsAffected if Ceph authentication (cephx) is configured and active on the cluster
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Inspect libceph authentication pathReview logs or trace authentication handshake events between Ceph clients and monitors. In debugging mode, look for process_auth_done function calls during connection establishmentAffected if The system performs Ceph authentication operations where process_auth_done() handles key material
The environment is affected if the system runs a vulnerable Linux kernel version from the listed ranges AND utilizes libceph for Ceph authentication, where key length validation in process_auth_done() can be bypassed.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped5.15.2026.1.1656.6.128
Apply the kernel patch that introduces CEPH_MAX_KEY_LEN bounds checking in process_auth_done(). Restrict network access to Ceph cluster management ports until the patch is deployed.
Upgrade to kernel version 6.12.75 or later (or 6.6.128+, 6.1.165+, or 5.15.202+ depending on branch preference)
- 1. Identify the current kernel version using 'uname -r' or 'cat /proc/version'
- 2. Verify the running kernel version is within the affected range (>= 5.11, < 5.15.202 OR >= 5.16, < 6.1.165 OR >= 6.2, < 6.6.128 OR >= 6.7, < 6.12.75)
- 3. Schedule a maintenance window for the kernel upgrade and reboot
- 4. Update the system package manager and install a kernel version >= 5.15.202, >= 6.1.165, >= 6.6.128, or >= 6.12.75 (prefer the latest stable release such as 6.12.75 or later)
- 5. After installation, update GRUB bootloader configuration if needed using 'update-grub' or 'grub2-mkconfig'
- 6. Reboot the system to load the patched kernel
- 7. Verify the new kernel version is running and is no longer in the affected range using 'uname -r'
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Linux Kernel
Scoped from the published advisory
- Consultation2.0 h
- Implementation4.0 h
- Testing6.0 h
- Review / QA3.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,096.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-43304 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-43304 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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