CVE-2026-64359nilfs2: reject CLEAN_SEGMENTS ioctl with out-of-range segment numbers
- 5.5MediumCVSS base score
- 0.12%Exploitation in 30 daysEPSS · top 98% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
In the Linux kernel, the following vulnerability has been resolved: nilfs2: reject CLEAN_SEGMENTS ioctl with out-of-range segment numbers Syzbot reported a hung task in nilfs_transaction_begin() where multiple tasks performing chmod() on a nilfs2 mount blocked for over 143 seconds waiting to acquire ns_segctor_sem for read: INFO: task syz.0.17:5918 blocked for more than 143 seconds. Call Trace: schedule+0x164/0x360 rwsem_down_read_slowpath+0x6d9/0x940 down_read+0x99/0x2e0 nilfs_transaction_begin+0x364/0x710 fs/nilfs2/segment.c:221 nilfs_setattr+0x124/0x2c0 fs/nilfs2/inode.c:921 notify_change+0xc1a/0xf40 chmod_common+0x273/0x4a0 do_fchmodat+0x12d/0x230 The writer holding ns_segctor_sem was a concurrent NILFS_IOCTL_CLEAN_SEGMENTS caller, stuck inside printk while emitting per-element warnings from nilfs_sufile_updatev(): __nilfs_msg+0x373/0x450 fs/nilfs2/super.c:78 nilfs_sufile_updatev+0x21c/0x6d0 fs/nilfs2/sufile.c:186 nilfs_sufile_freev fs/nilfs2/sufile.h:93 [inline] nilfs_free_segments fs/nilfs2/segment.c:1140 [inline] nilfs_segctor_collect_blocks fs/nilfs2/segment.c:1261 [inline] nilfs_segctor_do_construct+0x1f55/0x76c0 nilfs_clean_segments+0x3bd/0xa50 nilfs_ioctl_clean_segments fs/nilfs2/ioctl.c:922 [inline] nilfs_ioctl+0x261f/0x2780 The root cause is that user-supplied segment numbers are not validated before nilfs_clean_segments() begins doing work; the range check on each segnum is performed deep inside the call chain by nilfs_sufile_updatev(), which emits a nilfs_warn() per invalid entry while still holding the segctor lock and the sufile mi_sem. Under load (repeated invocations across multiple mounts saturating the global printk path), the cumulative printk latency keeps ns_segctor_sem held long enough to trip the hung_task watchdog, blocking concurrent operations such as chmod() that need ns_segctor_sem for read. Fix by validating the contents of kbufs[4] in nilfs_clean_segments() immediately after acquiring ns_segctor_sem via nilfs_transaction_lock(). Holding ns_segctor_sem serializes the check against nilfs_ioctl_resize(), which can modify ns_nsegments, so the validation uses a consistent value. Out-of-range segment numbers are rejected with -EINVAL before any segment-cleaning work begins, so the bad entries never reach the per-element diagnostic path inside nilfs_sufile_updatev().
Timeline
ID reserved
By Linux
- 6 days later
· 6 days later
Published
- 23 days later
· 23 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Analyzed | 3.1 | Medium5.5 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 0.12% · top 98% of all CVEs (14 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.5.
Affected products
- affected 071cb4b81987a28c7ac2702003cff3e61684a630 – < 3ed388ec3b8922383d1e2d4432d7bd4cbbf8364e
- affected 071cb4b81987a28c7ac2702003cff3e61684a630 – < 876c98e0fc65f071680c03c2e2ee3ef7ff9ca078
- affected 071cb4b81987a28c7ac2702003cff3e61684a630 – < 39607452b1400c7bf748f15122df4d058b768c5b
- affected 071cb4b81987a28c7ac2702003cff3e61684a630 – < 286f77d002a337735c0846d7480a82d9cda2aa31
- affected 071cb4b81987a28c7ac2702003cff3e61684a630 – < 0789f0a6710713254a08f3a7d2ecbb6d1cbcf0aa
- affected 071cb4b81987a28c7ac2702003cff3e61684a630 – < 223463c488b0554212a94de971ea538eb2805fc7
- affected 071cb4b81987a28c7ac2702003cff3e61684a630 – < d26aef771b4f6923da9f89d6d5b70d8def5853de
- affected 071cb4b81987a28c7ac2702003cff3e61684a630 – < 0e7a690fe435f8d5ea3feb7c1d8d73ba7e8b8aa9
- affected 2.6.31
- unaffected < 2.6.31
- unaffected 5.10.261 – ≤ 5.10.*
- unaffected 5.15.212 – ≤ 5.15.*
- unaffected 6.1.178 – ≤ 6.1.*
- unaffected 6.6.145 – ≤ 6.6.*
- unaffected 6.12.96 – ≤ 6.12.*
- unaffected 6.18.39 – ≤ 6.18.*
- unaffected 7.1.4 – ≤ 7.1.*
- unaffected 7.2 – ≤ *
References
References8
- https://git.kernel.org/stable/c/3ed388ec3b8922383d1e2d4432d7bd4cbbf8364e (opens in a new tab)
- https://git.kernel.org/stable/c/876c98e0fc65f071680c03c2e2ee3ef7ff9ca078 (opens in a new tab)
- https://git.kernel.org/stable/c/39607452b1400c7bf748f15122df4d058b768c5b (opens in a new tab)
- https://git.kernel.org/stable/c/286f77d002a337735c0846d7480a82d9cda2aa31 (opens in a new tab)
- https://git.kernel.org/stable/c/0789f0a6710713254a08f3a7d2ecbb6d1cbcf0aa (opens in a new tab)
- https://git.kernel.org/stable/c/223463c488b0554212a94de971ea538eb2805fc7 (opens in a new tab)
- https://git.kernel.org/stable/c/d26aef771b4f6923da9f89d6d5b70d8def5853de (opens in a new tab)
- https://git.kernel.org/stable/c/0e7a690fe435f8d5ea3feb7c1d8d73ba7e8b8aa9 (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-48903 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-64359)Record last updated .