CVE-2026-31395

Description

In the Linux kernel, the following vulnerability has been resolved: bnxt_en: fix OOB access in DBG_BUF_PRODUCER async event handler The ASYNC_EVENT_CMPL_EVENT_ID_DBG_BUF_PRODUCER handler in bnxt_async_event_process() uses a firmware-supplied 'type' field directly as an index into bp->bs_trace[] without bounds validation. The 'type' field is a 16-bit value extracted from DMA-mapped completion ring memory that the NIC writes directly to host RAM. A malicious or compromised NIC can supply any value from 0 to 65535, causing an out-of-bounds access into kernel heap memory. The bnxt_bs_trace_check_wrap() call then dereferences bs_trace->magic_byte and writes to bs_trace->last_offset and bs_trace->wrapped, leading to kernel memory corruption or a crash. Fix by adding a bounds check and defining BNXT_TRACE_MAX as DBG_LOG_BUFFER_FLUSH_REQ_TYPE_ERR_QPC_TRACE + 1 to cover all currently defined firmware trace types (0x0 through 0xc).

CVSS Details

CVSS Score

7.1

Severity

HIGH

CVSS Vector

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

Configurations (Affected Products)

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

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

cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:* - VULNERABLE

cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:* - VULNERABLE

Linux Kernel (受影响版本)

PoC / Exploit Code

⚠ For Security Research Only

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

python

/*
 * PoC Concept for CVE-2026-31395
 * This code simulates the vulnerable logic in the kernel driver.
 * In a real scenario, the 'type' value comes from a malicious NIC.
 */

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

#define BNXT_TRACE_MAX 13 // 0x0 to 0xc (Fixed size)

// Simulating the structure in kernel memory
struct bnxt_bs_trace {
    uint32_t magic_byte;
    uint32_t last_offset;
    uint32_t wrapped;
};

// Simulated vulnerable function logic
void vulnerable_handler(uint16_t type, struct bnxt_bs_trace *bp_bs_trace) {
    printf("[VULNERABLE] Received event with type: %d\n", type);
    
    // VULNERABILITY: No bounds check on 'type' before using it as an index
    // If type is 0xFFFF, this accesses memory way outside the array bounds
    struct bnxt_bs_trace *bs_trace = &bp_bs_trace[type]; 

    // This leads to out-of-bounds write/corruption
    bs_trace->last_offset = 0xDEADBEEF; 
    bs_trace->wrapped = 1;

    printf("[CRASH] Writing to address %p (Out of Bounds!)\n", bs_trace);
}

int main() {
    // Allocate a small buffer to simulate bp->bs_trace[]
    struct bnxt_bs_trace *trace_buffer = (struct bnxt_bs_trace*)malloc(sizeof(struct bnxt_bs_trace) * BNXT_TRACE_MAX);
    
    // Simulate a malicious NIC sending a large 'type' value (e.g., 65535)
    uint16_t malicious_type = 65535;
    
    // Trigger the vulnerability
    vulnerable_handler(malicious_type, trace_buffer);
    
    free(trace_buffer);
    return 0;
}

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-31395
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-31395
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-31395/
[4] VulDB https://vuldb.com/cve/CVE-2026-31395
[5] https://git.kernel.org/stable/c/19aa416eed9e4aaf1bbe8da0f7bd9a9be31158c8
[6] https://git.kernel.org/stable/c/64dcbde7f8f870a4f2d9daf24ffb06f9748b5dd3
[7] https://git.kernel.org/stable/c/b7c7a275447c6d4bf4a36a134682e2e4e20efd4b

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-31395", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-04-03T16:16:37.743", "lastModified": "2026-05-20T15:07:07.773", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbnxt_en: fix OOB access in DBG_BUF_PRODUCER async event handler\n\nThe ASYNC_EVENT_CMPL_EVENT_ID_DBG_BUF_PRODUCER handler in\nbnxt_async_event_process() uses a firmware-supplied 'type' field\ndirectly as an index into bp->bs_trace[] without bounds validation.\n\nThe 'type' field is a 16-bit value extracted from DMA-mapped completion\nring memory that the NIC writes directly to host RAM. A malicious or\ncompromised NIC can supply any value from 0 to 65535, causing an\nout-of-bounds access into kernel heap memory.\n\nThe bnxt_bs_trace_check_wrap() call then dereferences bs_trace->magic_byte\nand writes to bs_trace->last_offset and bs_trace->wrapped, leading to\nkernel memory corruption or a crash.\n\nFix by adding a bounds check and defining BNXT_TRACE_MAX as\nDBG_LOG_BUFFER_FLUSH_REQ_TYPE_ERR_QPC_TRACE + 1 to cover all currently\ndefined firmware trace types (0x0 through 0xc)."}], "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:N/A:H", "baseScore": 7.1, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 5.2}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-125"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"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: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/19aa416eed9e4aaf1bbe8da0f7bd9a9be31158c8", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/64dcbde7f8f870a4f2d9daf24ffb06f9748b5dd3", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/b7c7a275447c6d4bf4a36a134682e2e4e20efd4b", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}