CVE-2026-31663

Description

In the Linux kernel, the following vulnerability has been resolved: xfrm: hold dev ref until after transport_finish NF_HOOK After async crypto completes, xfrm_input_resume() calls dev_put() immediately on re-entry before the skb reaches transport_finish. The skb->dev pointer is then used inside NF_HOOK and its okfn, which can race with device teardown. Remove the dev_put from the async resumption entry and instead drop the reference after the NF_HOOK call in transport_finish, using a saved device pointer since NF_HOOK may consume the skb. This covers NF_DROP, NF_QUEUE and NF_STOLEN paths that skip the okfn. For non-transport exits (decaps, gro, drop) and secondary async return points, release the reference inline when async is set.

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 (修复前版本)

PoC / Exploit Code

⚠ For Security Research Only

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

python

/*
 * Conceptual PoC for CVE-2026-31663
 * Demonstrating the race condition between dev_put and NF_HOOK usage.
 */
#include <linux/module.h>
#include <linux/skbuff.h>
#include <net/xfrm.h>

void simulated_vulnerable_path(struct sk_buff *skb) {
    // Vulnerability: Reference is dropped here
    dev_put(skb->dev);

    // Race Window: If device teardown happens now, skb->dev is invalid.
    // But NF_HOOK below still uses it.
    NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, skb, skb->dev, NULL, NULL);
}

/*
 * Mitigation logic (Fix):
 * 1. Save the device pointer.
 * 2. Call NF_HOOK.
 * 3. Call dev_put(saved_dev) after the hook.
 */

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-31663
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-31663
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-31663/
[4] VulDB https://vuldb.com/cve/CVE-2026-31663
[5] https://git.kernel.org/stable/c/0f451b43c88bf2b9c038b414be580efee42e031b
[6] https://git.kernel.org/stable/c/1c428b03840094410c5fb6a5db30640486bbbfcb
[7] https://git.kernel.org/stable/c/5002beda5cac69d522dc54da0d5d463ed9c963d2

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-31663", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-04-24T15:16:45.947", "lastModified": "2026-04-27T19:59:32.810", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nxfrm: hold dev ref until after transport_finish NF_HOOK\n\nAfter async crypto completes, xfrm_input_resume() calls dev_put()\nimmediately on re-entry before the skb reaches transport_finish.\nThe skb->dev pointer is then used inside NF_HOOK and its okfn,\nwhich can race with device teardown.\n\nRemove the dev_put from the async resumption entry and instead\ndrop the reference after the NF_HOOK call in transport_finish,\nusing a saved device pointer since NF_HOOK may consume the skb.\nThis covers NF_DROP, NF_QUEUE and NF_STOLEN paths that skip\nthe okfn.\n\nFor non-transport exits (decaps, gro, drop) and secondary\nasync return points, release the reference inline when\nasync is set."}], "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": "NVD-CWE-noinfo"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.2.100", "versionEndExcluding": "3.3", "matchCriteriaId": "6B10F87F-6387-4CE3-9159-D77EB163C9AD"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.16.55", "versionEndExcluding": "3.17", "matchCriteriaId": "C9F9D919-846F-4FDC-882F-B49219EA19E9"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.14.24", "versionEndExcluding": "4.15", "matchCriteriaId": "4C6AA567-92EC-46CF-9ED1-2B04B2B29BFB"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.15.1", "versionEndExcluding": "6.18.23", "matchCriteriaId": "45125EC8-B49D-48DD-92B9-2E4D1295531E"}, {"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:4.15:-:*:*:*:*:*:*", "matchCriteriaId": "3B4D39AF-668B-442B-8085-639A6D4FA5AC"}, {"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/0f451b43c88bf2b9c038b414be580efee42e031b", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/1c428b03840094410c5fb6a5db30640486bbbfcb", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/5002beda5cac69d522dc54da0d5d463ed9c963d2", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}