FreeBSD Fusefs Kernel heap-based overflow

CVSS Meta Temp Score
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CTI Interest Score
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6.6$5k-$25k0.00

Summaryinfo

A vulnerability categorized as critical has been discovered in FreeBSD. This affects an unknown function of the component Fusefs Kernel Module. Such manipulation leads to heap-based overflow. This vulnerability is listed as CVE-2026-45252. There is no available exploit. It is advisable to implement a patch to correct this issue.

Detailsinfo

A vulnerability, which was classified as critical, has been found in FreeBSD (affected version unknown). Affected by this issue is an unknown functionality of the component Fusefs Kernel Module. The manipulation with an unknown input leads to a heap-based overflow vulnerability. Using CWE to declare the problem leads to CWE-122. A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc(). Impacted is confidentiality, integrity, and availability. CVE summarizes:

When 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.

The weakness was presented with AISLE Research Team. The advisory is shared for download at security.freebsd.org. This vulnerability is handled as CVE-2026-45252 since 05/11/2026. The exploitation is known to be easy. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $5k-$25k (estimation calculated on 05/24/2026).

Applying a patch is able to eliminate this problem.

The vulnerability is also documented in the databases at EUVD (EUVD-2026-31254) and CERT Bund (WID-SEC-2026-1628). Once again VulDB remains the best source for vulnerability data.

Affected

  • FreeBSD Project FreeBSD OS

Productinfo

Type

Name

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.8
VulDB Meta Temp Score: 6.6

VulDB Base Score: 8.0
VulDB Temp Score: 7.6
VulDB Vector: 🔒
VulDB Reliability: 🔍

ADP CISA Base Score: 5.5
ADP CISA Vector: 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Heap-based overflow
CWE: CWE-122 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Patch
Status: 🔍

0-Day Time: 🔒

Timelineinfo

05/11/2026 CVE reserved
05/21/2026 +10 days Advisory disclosed
05/21/2026 +0 days VulDB entry created
05/24/2026 +3 days VulDB entry last update

Sourcesinfo

Product: freebsd.org

Advisory: security.freebsd.org
Organization: AISLE Research Team
Status: Confirmed

CVE: CVE-2026-45252 (🔒)
GCVE (CVE): GCVE-0-2026-45252
GCVE (VulDB): GCVE-100-364988
EUVD: 🔒
CERT Bund: WID-SEC-2026-1628 - FreeBSD Project FreeBSD OS: Mehrere Schwachstellen

Entryinfo

Created: 05/21/2026 12:42
Updated: 05/24/2026 05:39
Changes: 05/21/2026 12:42 (54), 05/21/2026 14:53 (7), 05/21/2026 15:20 (1), 05/24/2026 05:39 (11)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

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