CVE-2026-64326

In the Linux kernel, the following vulnerability has been resolved: block: skip sync_blockdev() on surprise removal in bdev_mark_dead() bdev_mark_dead()'s @surprise == true means the device is already gone. The filesystem callback fs_bdev_mark_dead() honours this and skips sync_filesystem(), but the bare block device path (no ->mark_dead op) lost its !surprise guard when the holder ->mark_dead callback was wired up (see Fixes), and now calls sync_blockdev() unconditionally, which can hang forever waiting on writeback that can no longer complete. syzkaller hit this via nvme_reset_work()'s "I/O queues lost" path: nvme_mark_namespaces_dead() -> blk_mark_disk_dead() -> bdev_mark_dead(bdev, true) -> sync_blockdev() blocks in folio_wait_writeback(), wedging the reset worker and every task waiting on it. Skip the sync on surprise removal, matching fs_bdev_mark_dead(); invalidate_bdev() still runs. Orderly removal (surprise == false) is unchanged. Found by FuzzNvme(Syzkaller with FEMU fuzzing framework).

CVSS v3 5.5 MEDIUM

5.5^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 1.8 / Impact : 3.6

Attack Vector LOCAL

Attack Complexity LOW

Privileges Required LOW

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://git.kernel.org/stable/c/49f06cff50a4ccf3b7a1a662ceb892b3b21a527a	Patch
https://git.kernel.org/stable/c/9818bcae3c0ca1dde4b9a334125c46676e0a9b29	Patch
https://git.kernel.org/stable/c/aa4c4a9315764b2b7a7182e72cc5ea87520436b4	Patch
https://git.kernel.org/stable/c/d6998ddd507c81e3829489a6ead23f17f5acb7fe	Patch
https://git.kernel.org/stable/c/f41cf35ee2a1e31374b3f54e7579c55153506e70	Patch

Configurations

Configuration 1 (hide)

OR	cpe:2.3:o:linux:linux_kernel::::::::
	cpe:2.3:o:linux:linux_kernel::::::::
	cpe:2.3:o:linux:linux_kernel::::::::
	cpe:2.3:o:linux:linux_kernel::::::::

History

No history.

Information

Published : 2026-07-25 10:17

Updated : 2026-09-04 14:51

NVD link : CVE-2026-64326

Mitre link : CVE-2026-64326

CVE.ORG link : CVE-2026-64326

JSON object : View

Products Affected

linux

linux_kernel

CWE

NVD-CWE-noinfo

{"id": "CVE-2026-64326", "cveTags": [], "metrics": {"cvssMetricV31": [{"type": "Primary", "source": "nvd@nist.gov", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 5.5, "attackVector": "LOCAL", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "NONE"}, "impactScore": 3.6, "exploitabilityScore": 1.8}]}, "affected": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "affectedData": [{"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "d8530de5a6e82be0ce17a5fdf727a394bcf6444c", "lessThan": "d6998ddd507c81e3829489a6ead23f17f5acb7fe", "versionType": "git"}, {"status": "affected", "version": "d8530de5a6e82be0ce17a5fdf727a394bcf6444c", "lessThan": "f41cf35ee2a1e31374b3f54e7579c55153506e70", "versionType": "git"}, {"status": "affected", "version": "d8530de5a6e82be0ce17a5fdf727a394bcf6444c", "lessThan": "9818bcae3c0ca1dde4b9a334125c46676e0a9b29", "versionType": "git"}, {"status": "affected", "version": "d8530de5a6e82be0ce17a5fdf727a394bcf6444c", "lessThan": "aa4c4a9315764b2b7a7182e72cc5ea87520436b4", "versionType": "git"}, {"status": "affected", "version": "d8530de5a6e82be0ce17a5fdf727a394bcf6444c", "lessThan": "49f06cff50a4ccf3b7a1a662ceb892b3b21a527a", "versionType": "git"}], "programFiles": ["block/bdev.c"], "defaultStatus": "unaffected"}, {"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "6.6"}, {"status": "unaffected", "version": "0", "lessThan": "6.6", "versionType": "semver"}, {"status": "unaffected", "version": "6.6.145", "versionType": "semver", "lessThanOrEqual": "6.6.*"}, {"status": "unaffected", "version": "6.12.96", "versionType": "semver", "lessThanOrEqual": "6.12.*"}, {"status": "unaffected", "version": "6.18.39", "versionType": "semver", "lessThanOrEqual": "6.18.*"}, {"status": "unaffected", "version": "7.1.4", "versionType": "semver", "lessThanOrEqual": "7.1.*"}, {"status": "unaffected", "version": "7.2", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*"}], "programFiles": ["block/bdev.c"], "defaultStatus": "affected"}]}], "published": "2026-07-25T10:17:14.207", "references": [{"url": "https://git.kernel.org/stable/c/49f06cff50a4ccf3b7a1a662ceb892b3b21a527a", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/9818bcae3c0ca1dde4b9a334125c46676e0a9b29", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/aa4c4a9315764b2b7a7182e72cc5ea87520436b4", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/d6998ddd507c81e3829489a6ead23f17f5acb7fe", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/f41cf35ee2a1e31374b3f54e7579c55153506e70", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Primary", "source": "nvd@nist.gov", "description": [{"lang": "en", "value": "NVD-CWE-noinfo"}]}], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nblock: skip sync_blockdev() on surprise removal in bdev_mark_dead()\n\nbdev_mark_dead()'s @surprise == true means the device is already gone.\nThe filesystem callback fs_bdev_mark_dead() honours this and skips\nsync_filesystem(), but the bare block device path (no ->mark_dead op)\nlost its !surprise guard when the holder ->mark_dead callback was wired\nup (see Fixes), and now calls sync_blockdev() unconditionally, which can\nhang forever waiting on writeback that can no longer complete.\n\nsyzkaller hit this via nvme_reset_work()'s \"I/O queues lost\" path:\nnvme_mark_namespaces_dead() -> blk_mark_disk_dead() ->\nbdev_mark_dead(bdev, true) -> sync_blockdev() blocks in\nfolio_wait_writeback(), wedging the reset worker and every task waiting\non it.\n\nSkip the sync on surprise removal, matching fs_bdev_mark_dead();\ninvalidate_bdev() still runs. Orderly removal (surprise == false) is\nunchanged.\n\nFound by FuzzNvme(Syzkaller with FEMU fuzzing framework)."}], "lastModified": "2026-09-04T14:51:12.160", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "E3FA344C-B942-4687-A4B0-6BCB10437FC1", "versionEndExcluding": "6.6.145", "versionStartIncluding": "6.6"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "38A8100E-2B1A-462F-AEE9-8901B870FEF2", "versionEndExcluding": "6.12.96", "versionStartIncluding": "6.7"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "914AE4BC-3D59-4C5A-9DB5-9CE327B429F7", "versionEndExcluding": "6.18.39", "versionStartIncluding": "6.13"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "6228DDD6-4557-4AA3-9F43-AB995D471E42", "versionEndExcluding": "7.1.4", "versionStartIncluding": "6.19"}], "operator": "OR"}]}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}