CVE-2025-0662 Overview
CVE-2025-0662 is a kernel information disclosure vulnerability in the FreeBSD ktrace facility. The ktrace subsystem logs kernel structure contents to userspace for tracing purposes. When dumping a variable-sized sockaddr structure, the code copies the full structure size even when the actual sockaddr is shorter. This behavior exposes up to 14 uninitialized bytes of kernel heap memory to unprivileged userspace programs. The flaw is categorized under [CWE-122] (Heap-based Buffer Overflow), reflecting the underlying heap memory handling error. An unprivileged local process can trigger the leak and read residual kernel data.
Critical Impact
An unprivileged userspace program can leak up to 14 bytes of kernel heap memory per invocation, potentially exposing sensitive kernel data and undermining address space layout randomization.
Affected Products
- FreeBSD (see FreeBSD Security Advisory SA-25:04 for affected versions)
- NetApp products (see NetApp Security Advisory NTAP-20250207-0006)
Discovery Timeline
- 2025-01-30 - CVE-2025-0662 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-0662
Vulnerability Analysis
The FreeBSD ktrace facility records kernel-level events, including system call arguments, to userspace trace files. During this process, ktrace serializes kernel structures for consumers to read. One code path dumps a sockaddr structure, which is variable in length depending on the address family. The implementation copies the maximum sockaddr size rather than the actual length declared by sa_len. When the real sockaddr is shorter than the maximum, the trailing bytes originate from uninitialized kernel heap memory. Those bytes can contain fragments of prior allocations, including pointers, cryptographic material, or other sensitive kernel state.
Root Cause
The root cause is a length mismatch between the declared sockaddr size and the number of bytes copied to userspace. The ktrace copy operation trusts a fixed buffer size instead of using the sockaddr's actual sa_len field. Because the kernel heap allocation is not zero-initialized before use, residual data remains readable to unprivileged callers.
Attack Vector
An attacker with local access runs an unprivileged program that triggers ktrace on itself and issues syscalls carrying short sockaddr arguments. The attacker then reads the resulting trace file and extracts the uninitialized trailing bytes. Repeated invocations increase the volume of leaked kernel memory and improve the odds of recovering high-value data. No elevated privileges or user interaction are required for exploitation. The vulnerability does not permit code execution or data modification.
No public proof-of-concept code is currently associated with this CVE. See the FreeBSD Security Advisory SA-25:04 for authoritative technical details.
Detection Methods for CVE-2025-0662
Indicators of Compromise
- Unexpected creation of ktrace output files (ktrace.out or user-specified paths) by unprivileged accounts.
- Processes invoking the ktrace(2) or utrace(2) syscalls outside of legitimate debugging workflows.
- Repeated short-lived processes generating trace files followed by reads of those files.
Detection Strategies
- Audit FreeBSD system call telemetry for anomalous use of ktrace(2), kdump(1), and related tracing utilities by non-administrative users.
- Correlate trace file creation with syscalls that pass sockaddr arguments, such as bind, connect, and sendto.
- Baseline legitimate developer and administrator usage of ktrace, then alert on deviations from that baseline.
Monitoring Recommendations
- Enable file integrity and process monitoring on FreeBSD hosts to capture ktrace invocations and output file access.
- Forward FreeBSD audit logs (auditd) to a centralized analytics platform for retention and correlation.
- Review multi-tenant systems, jails, and shared build hosts where unprivileged users can execute arbitrary code.
How to Mitigate CVE-2025-0662
Immediate Actions Required
- Apply the FreeBSD security patch referenced in FreeBSD Security Advisory SA-25:04 on all affected hosts.
- Review NetApp Security Advisory NTAP-20250207-0006 and apply vendor updates for NetApp products that embed the affected FreeBSD components.
- Reboot systems after patch installation to ensure the corrected kernel is active.
Patch Information
FreeBSD has released patches addressing the truncated copy behavior in ktrace. The fix ensures that only the declared sockaddr length is copied to userspace, preventing exposure of uninitialized bytes. Consult the FreeBSD Security Advisory SA-25:04 for exact revision identifiers, source patches, and freebsd-update instructions applicable to each supported release.
Workarounds
- Restrict use of the ktrace(2) facility to trusted users where feasible, using system policy or jail configuration.
- Limit interactive shell access on multi-tenant FreeBSD hosts to reduce the local attack surface until patches are deployed.
- Monitor for creation of ktrace output files by unprivileged users and treat unexpected occurrences as investigative leads.
# Apply the FreeBSD binary patch using freebsd-update
freebsd-update fetch
freebsd-update install
# Reboot to activate the patched kernel
shutdown -r now
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
