Kernel heap disclosure and corruption via unchecked strlen
Published May 21, 2026 · Updated May 21, 2026
Heap overflow in FreeBSD fusefs allows attackers controlling a malicious FUSE daemon to expose or corrupt kernel heap memory. The fusefs kernel module calls strlen() on a daemon-supplied FUSE_LISTXATTR buffer without verifying that its packed string list ends in NUL bytes. A malicious daemon can trigger an out-of-bounds read exposing up to 253 bytes or an out-of-bounds write injecting up to 250 bytes into kernel heap space.
Summary
What happened
Heap overflow in FreeBSD fusefs allows attackers controlling a malicious FUSE daemon to expose or corrupt kernel heap memory. The fusefs kernel module calls strlen() on a daemon-supplied FUSE_LISTXATTR buffer without verifying that its packed string list ends in NUL bytes. A malicious daemon can trigger an out-of-bounds read exposing up to 253 bytes or an out-of-bounds write injecting up to 250 bytes into kernel heap space.
The record
- CVE
- CVE-2026-45252
- Published
- May 21, 2026
- Updated
- May 21, 2026
- Vendor
- The FreeBSD Project
- Product
- FreeBSD
- Classifications
- CWE-122, T1005
- Attack vector
- network
- Privileges
- admin
Timeline
How it unfolded
- May 21, 2026CVE publishedPublication date reported by the CVE source.
- May 21, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=14.3-RELEASE <p14
- Affected versionversion=14.4-RELEASE <p5
- Affected versionversion=15.0-RELEASE <p9
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
No public exploit references are available in this record.
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo