FreeBSDOperating system
CVE-2026-45252
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 · uneditedWhen a fusefs file system implements extended attributes, the kernel may send a FUSE_LISTXATTR message to the userspace daemon to retrieve the list of extended attributes for a given file. The FUSE protocol requires the daemon to return a packed list of NUL-terminated strings. The fusefs kernel module calls strlen() on this daemon-supplied buffer without first verifying that the entire list is NUL-terminated. If a malicious daemon sends a non-NUL-terminated list, the fusefs kernel module may read beyond the end of one heap-allocated buffer and potentially write beyond the end of a second buffer. A malicious daemon could disclose up to 253 bytes of kernel heap memory, or it could inject up to 250 attacker-controlled bytes into unallocated kernel heap space.
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 · high confidenceThe Linux kernel's fusefs module has a buffer over-read and over-write vulnerability in the FUSE_LISTXATTR handler. When a FUSE daemon returns extended attribute lists, the kernel calls strlen() on the daemon-supplied buffer without verifying it is NUL-terminated, allowing a malicious daemon to read up to 253 bytes beyond the buffer and potentially write up to 250 bytes beyond a second heap buffer.
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
FreeBSDOperating system
= 14.3= 14.4= 15.0CVSS 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
- High
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- Low
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:N/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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Check FreeBSD versionRun 'uname -r' or 'freebsd-version -u' to determine the installed FreeBSD versionAffected if The version is 14.3, 14.4, or 15.0
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Verify FUSE kernel module availabilityRun 'kldstat -v | grep fuse' or check if /dev/fuse existsAffected if The FUSE kernel module (fuse.ko) is loaded or loadable
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Identify mounted FUSE filesystemsRun 'mount | grep -i fuse' to list any actively mounted FUSE-based filesystemsAffected if Any FUSE filesystems are currently mounted and in use
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Check for xattr usage on FUSE mountsRun 'getfattr -d -m . <path>' or 'listxattr <path>' on a mounted FUSE filesystem to test extended attribute operationsAffected if Extended attributes can be listed or retrieved from a FUSE-mounted filesystem
A user is affected if running FreeBSD 14.3, 14.4, or 15.0 with the FUSE kernel module loaded and FUSE filesystems that support extended attributes are in use.
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.
From vendor dataThe fix requires modifying the kernel's fusefs code to verify NUL-termination of the extended attribute list buffer before calling strlen(), adding proper bounds checking and ensuring the buffer is large enough to contain the complete NUL-terminated string list.
Fix this in FreeBSD
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing8.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,656.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-45252 — 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-2026-45252 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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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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