CVE-2026-31554

Description

In the Linux kernel, the following vulnerability has been resolved: futex: Require sys_futex_requeue() to have identical flags Nicholas reported that his LLM found it was possible to create a UaF when sys_futex_requeue() is used with different flags. The initial motivation for allowing different flags was the variable sized futex, but since that hasn't been merged (yet), simply mandate the flags are identical, as is the case for the old style sys_futex() requeue operations.

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

cpe:2.3:o:linux:linux_kernel:6.7:-:*:*:*:*:*:* - VULNERABLE

cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:* - VULNERABLE

Linux Kernel (Commit 027145ace09fad4c7cbcd6c61fe9b429c63eb0e5 之前版本)

Linux Kernel (Commit 18b7d09c2b794c71d4252f3ea2cf84ad12b73d6a 之前版本)

Linux Kernel (Commit 19f94b39058681dec64a10ebeb6f23fe7fc3f77a 之前版本)

Linux Kernel (Commit e2f78c7ec1655fedd945366151ba54fcb9580508 之前版本)

PoC / Exploit Code

⚠ For Security Research Only

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

python

#include <stdio.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <linux/futex.h>
#include <stdint.h>

// Conceptual PoC for CVE-2026-31554
// Demonstrates the logic of triggering the bug with mismatched flags

#define FUTEX_PRIVATE_FLAG 128
#define FUTEX_REQUEUE 13

int main() {
    uint32_t futex1 = 0;
    uint32_t futex2 = 0;
    int flags1 = FUTEX_PRIVATE_FLAG;
    int flags2 = 0; // Use different flags to trigger the bug

    printf("[*] Triggering sys_futex_requeue with mismatched flags...\n");

    // In a real scenario, this would involve setting up waiters
    // and then calling the syscall to induce the UaF condition.
    // syscall(SYS_futex, &futex1, FUTEX_REQUEUE | flags1, 1, 0, &futex2, flags2);

    // This is a placeholder for the exploitation logic.
    printf("[!] Potential UaF triggered.\n");
    return 0;
}

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-31554
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-31554
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-31554/
[4] VulDB https://vuldb.com/cve/CVE-2026-31554
[5] https://git.kernel.org/stable/c/027145ace09fad4c7cbcd6c61fe9b429c63eb0e5
[6] https://git.kernel.org/stable/c/18b7d09c2b794c71d4252f3ea2cf84ad12b73d6a
[7] https://git.kernel.org/stable/c/19f94b39058681dec64a10ebeb6f23fe7fc3f77a
[8] https://git.kernel.org/stable/c/e2f78c7ec1655fedd945366151ba54fcb9580508

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-31554", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-04-24T15:16:29.730", "lastModified": "2026-04-27T20:14:55.107", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfutex: Require sys_futex_requeue() to have identical flags\n\nNicholas reported that his LLM found it was possible to create a UaF\nwhen sys_futex_requeue() is used with different flags. The initial\nmotivation for allowing different flags was the variable sized futex,\nbut since that hasn't been merged (yet), simply mandate the flags are\nidentical, as is the case for the old style sys_futex() requeue\noperations."}], "metrics": {"cvssMetricV31": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary", "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-416"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7.1", "versionEndExcluding": "6.12.80", "matchCriteriaId": "92943666-715A-42F1-AF8E-6D1419BD7D3E"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.21", "matchCriteriaId": "ED39847A-3B46-4729-B7CA-B2C30B9FA8FE"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.11", "matchCriteriaId": "4CA2E747-A9EC-4518-9AA2-B4247FC748B7"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.7:-:*:*:*:*:*:*", "matchCriteriaId": "62B55B1B-7D3E-499B-9C42-E9F1EF05A54A"}, {"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"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc7:*:*:*:*:*:*", "matchCriteriaId": "512EE3A8-A590-4501-9A94-5D4B268D6138"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/027145ace09fad4c7cbcd6c61fe9b429c63eb0e5", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/18b7d09c2b794c71d4252f3ea2cf84ad12b73d6a", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/19f94b39058681dec64a10ebeb6f23fe7fc3f77a", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/e2f78c7ec1655fedd945366151ba54fcb9580508", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}