CVE-2025-40237 (GCVE-0-2025-40237)
Vulnerability from cvelistv5 – Published: 2025-12-04 15:31 – Updated: 2026-05-23 16:01
VLAI
EPSS
VEX
Title
fs/notify: call exportfs_encode_fid with s_umount
Summary
In the Linux kernel, the following vulnerability has been resolved:
fs/notify: call exportfs_encode_fid with s_umount
Calling intotify_show_fdinfo() on fd watching an overlayfs inode, while
the overlayfs is being unmounted, can lead to dereferencing NULL ptr.
This issue was found by syzkaller.
Race Condition Diagram:
Thread 1 Thread 2
-------- --------
generic_shutdown_super()
shrink_dcache_for_umount
sb->s_root = NULL
|
| vfs_read()
| inotify_fdinfo()
| * inode get from mark *
| show_mark_fhandle(m, inode)
| exportfs_encode_fid(inode, ..)
| ovl_encode_fh(inode, ..)
| ovl_check_encode_origin(inode)
| * deref i_sb->s_root *
|
|
v
fsnotify_sb_delete(sb)
Which then leads to:
[ 32.133461] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000006: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI
[ 32.134438] KASAN: null-ptr-deref in range [0x0000000000000030-0x0000000000000037]
[ 32.135032] CPU: 1 UID: 0 PID: 4468 Comm: systemd-coredum Not tainted 6.17.0-rc6 #22 PREEMPT(none)
<snip registers, unreliable trace>
[ 32.143353] Call Trace:
[ 32.143732] ovl_encode_fh+0xd5/0x170
[ 32.144031] exportfs_encode_inode_fh+0x12f/0x300
[ 32.144425] show_mark_fhandle+0xbe/0x1f0
[ 32.145805] inotify_fdinfo+0x226/0x2d0
[ 32.146442] inotify_show_fdinfo+0x1c5/0x350
[ 32.147168] seq_show+0x530/0x6f0
[ 32.147449] seq_read_iter+0x503/0x12a0
[ 32.148419] seq_read+0x31f/0x410
[ 32.150714] vfs_read+0x1f0/0x9e0
[ 32.152297] ksys_read+0x125/0x240
IOW ovl_check_encode_origin derefs inode->i_sb->s_root, after it was set
to NULL in the unmount path.
Fix it by protecting calling exportfs_encode_fid() from
show_mark_fhandle() with s_umount lock.
This form of fix was suggested by Amir in [1].
[1]: https://lore.kernel.org/all/CAOQ4uxhbDwhb+2Brs1UdkoF0a3NSdBAOQPNfEHjahrgoKJpLEw@mail.gmail.com/
Severity
No CVSS data available.
Assigner
References
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
a1a541fbfa7e97c1100144db34b57553d7164ce5 , < 950b604384fd75d62e860bec7135b2b62eb4d508
(git)
Affected: f0c0ac84de17c37e6e84da65fb920f91dada55ad , < bc1c6b803e14ea2b8f7e33b7164013f666ceb656 (git) Affected: 3c7c90274ae339e1ad443c9be1c67a20b80b9c76 , < 3f307a9f7a7a2822e38ac451b73e2244e7279496 (git) Affected: c45beebfde34aa71afbc48b2c54cdda623515037 , < d1894bc542becb0fda61e7e513b09523cab44030 (git) Affected: c45beebfde34aa71afbc48b2c54cdda623515037 , < a7c4bb43bfdc2b9f06ee9d036028ed13a83df42a (git) Affected: 6.6.72 , < 6.6.73 (semver) Affected: 6.6.74 , < 6.6.115 (semver) Affected: 6.12.10 , < 6.12.56 (semver) |
guessed | |
| Linux | Linux |
Affected:
6.13
Unaffected: 0 , < 6.13 (semver) Unaffected: 6.6.73 , ≤ 6.6.* (semver) Unaffected: 6.6.115 , ≤ 6.6.* (semver) Unaffected: 6.12.56 , ≤ 6.12.* (semver) Unaffected: 6.17.6 , ≤ 6.17.* (semver) Unaffected: 6.18 , ≤ * (original_commit_for_fix) |
guessed |
{
"containers": {
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{
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"product": "Linux",
"programFiles": [
"fs/notify/fdinfo.c"
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{
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{
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"versionType": "semver"
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{
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"status": "unaffected",
"version": "6.17.6",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "6.18",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.6.73",
"versionStartIncluding": "6.6.72",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.6.115",
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},
{
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},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18",
"versionStartIncluding": "6.13",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfs/notify: call exportfs_encode_fid with s_umount\n\nCalling intotify_show_fdinfo() on fd watching an overlayfs inode, while\nthe overlayfs is being unmounted, can lead to dereferencing NULL ptr.\n\nThis issue was found by syzkaller.\n\nRace Condition Diagram:\n\nThread 1 Thread 2\n-------- --------\n\ngeneric_shutdown_super()\n shrink_dcache_for_umount\n sb-\u003es_root = NULL\n\n |\n | vfs_read()\n | inotify_fdinfo()\n | * inode get from mark *\n | show_mark_fhandle(m, inode)\n | exportfs_encode_fid(inode, ..)\n | ovl_encode_fh(inode, ..)\n | ovl_check_encode_origin(inode)\n | * deref i_sb-\u003es_root *\n |\n |\n v\n fsnotify_sb_delete(sb)\n\nWhich then leads to:\n\n[ 32.133461] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000006: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI\n[ 32.134438] KASAN: null-ptr-deref in range [0x0000000000000030-0x0000000000000037]\n[ 32.135032] CPU: 1 UID: 0 PID: 4468 Comm: systemd-coredum Not tainted 6.17.0-rc6 #22 PREEMPT(none)\n\n\u003csnip registers, unreliable trace\u003e\n\n[ 32.143353] Call Trace:\n[ 32.143732] ovl_encode_fh+0xd5/0x170\n[ 32.144031] exportfs_encode_inode_fh+0x12f/0x300\n[ 32.144425] show_mark_fhandle+0xbe/0x1f0\n[ 32.145805] inotify_fdinfo+0x226/0x2d0\n[ 32.146442] inotify_show_fdinfo+0x1c5/0x350\n[ 32.147168] seq_show+0x530/0x6f0\n[ 32.147449] seq_read_iter+0x503/0x12a0\n[ 32.148419] seq_read+0x31f/0x410\n[ 32.150714] vfs_read+0x1f0/0x9e0\n[ 32.152297] ksys_read+0x125/0x240\n\nIOW ovl_check_encode_origin derefs inode-\u003ei_sb-\u003es_root, after it was set\nto NULL in the unmount path.\n\nFix it by protecting calling exportfs_encode_fid() from\nshow_mark_fhandle() with s_umount lock.\n\nThis form of fix was suggested by Amir in [1].\n\n[1]: https://lore.kernel.org/all/CAOQ4uxhbDwhb+2Brs1UdkoF0a3NSdBAOQPNfEHjahrgoKJpLEw@mail.gmail.com/"
}
],
"providerMetadata": {
"dateUpdated": "2026-05-23T16:01:45.934Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
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"url": "https://git.kernel.org/stable/c/950b604384fd75d62e860bec7135b2b62eb4d508"
},
{
"url": "https://git.kernel.org/stable/c/bc1c6b803e14ea2b8f7e33b7164013f666ceb656"
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{
"url": "https://git.kernel.org/stable/c/3f307a9f7a7a2822e38ac451b73e2244e7279496"
},
{
"url": "https://git.kernel.org/stable/c/d1894bc542becb0fda61e7e513b09523cab44030"
},
{
"url": "https://git.kernel.org/stable/c/a7c4bb43bfdc2b9f06ee9d036028ed13a83df42a"
}
],
"title": "fs/notify: call exportfs_encode_fid with s_umount",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
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"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2025-40237",
"datePublished": "2025-12-04T15:31:27.325Z",
"dateReserved": "2025-04-16T07:20:57.181Z",
"dateUpdated": "2026-05-23T16:01:45.934Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
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"cve": "CVE-2025-40237",
"date": "2026-10-08",
"epss": "0.00201",
"percentile": "0.09142"
},
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}
]
}
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfs/notify: call exportfs_encode_fid with s_umount\n\nCalling intotify_show_fdinfo() on fd watching an overlayfs inode, while\nthe overlayfs is being unmounted, can lead to dereferencing NULL ptr.\n\nThis issue was found by syzkaller.\n\nRace Condition Diagram:\n\nThread 1 Thread 2\n-------- --------\n\ngeneric_shutdown_super()\n shrink_dcache_for_umount\n sb-\u003es_root = NULL\n\n |\n | vfs_read()\n | inotify_fdinfo()\n | * inode get from mark *\n | show_mark_fhandle(m, inode)\n | exportfs_encode_fid(inode, ..)\n | ovl_encode_fh(inode, ..)\n | ovl_check_encode_origin(inode)\n | * deref i_sb-\u003es_root *\n |\n |\n v\n fsnotify_sb_delete(sb)\n\nWhich then leads to:\n\n[ 32.133461] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000006: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI\n[ 32.134438] KASAN: null-ptr-deref in range [0x0000000000000030-0x0000000000000037]\n[ 32.135032] CPU: 1 UID: 0 PID: 4468 Comm: systemd-coredum Not tainted 6.17.0-rc6 #22 PREEMPT(none)\n\n\u003csnip registers, unreliable trace\u003e\n\n[ 32.143353] Call Trace:\n[ 32.143732] ovl_encode_fh+0xd5/0x170\n[ 32.144031] exportfs_encode_inode_fh+0x12f/0x300\n[ 32.144425] show_mark_fhandle+0xbe/0x1f0\n[ 32.145805] inotify_fdinfo+0x226/0x2d0\n[ 32.146442] inotify_show_fdinfo+0x1c5/0x350\n[ 32.147168] seq_show+0x530/0x6f0\n[ 32.147449] seq_read_iter+0x503/0x12a0\n[ 32.148419] seq_read+0x31f/0x410\n[ 32.150714] vfs_read+0x1f0/0x9e0\n[ 32.152297] ksys_read+0x125/0x240\n\nIOW ovl_check_encode_origin derefs inode-\u003ei_sb-\u003es_root, after it was set\nto NULL in the unmount path.\n\nFix it by protecting calling exportfs_encode_fid() from\nshow_mark_fhandle() with s_umount lock.\n\nThis form of fix was suggested by Amir in [1].\n\n[1]: https://lore.kernel.org/all/CAOQ4uxhbDwhb+2Brs1UdkoF0a3NSdBAOQPNfEHjahrgoKJpLEw@mail.gmail.com/"
}
],
"id": "CVE-2025-40237",
"lastModified": "2026-06-17T09:21:30.407",
"metrics": {},
"published": "2025-12-04T16:16:16.697",
"references": [
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/3f307a9f7a7a2822e38ac451b73e2244e7279496"
},
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"url": "https://git.kernel.org/stable/c/950b604384fd75d62e860bec7135b2b62eb4d508"
},
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"url": "https://git.kernel.org/stable/c/bc1c6b803e14ea2b8f7e33b7164013f666ceb656"
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}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Deferred"
}
},
"redhat_vex": {
"aggregate_severity": "Moderate",
"current_release_date": "2026-10-08T12:01:56+00:00",
"cve": "CVE-2025-40237",
"id": "CVE-2025-40237",
"initial_release_date": "2025-12-04T00:00:00+00:00",
"product_status:fixed": "616",
"product_status:known_affected": "108",
"product_status:known_not_affected": "90",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: fs/notify: call exportfs_encode_fid with s_umount",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-40237.json",
"version": "3"
},
"suse_vex": {
"aggregate_severity": "moderate",
"current_release_date": "2026-10-07T23:51:38Z",
"cve": "CVE-2025-40237",
"id": "CVE-2025-40237",
"initial_release_date": "2025-12-05T00:25:47Z",
"product_status:known_affected": "396",
"product_status:known_not_affected": "538",
"product_status:recommended": "214",
"source": "SUSE CSAF VEX",
"status": "interim",
"title": "SUSE CVE CVE-2025-40237",
"url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2025-40237.json",
"version": "30"
}
}
}
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Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
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- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
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- Not confirmed: The user expressed doubt about the validity of the vulnerability.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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