CVE-2026-53320 | nilfs2: reject zero bd_oblocknr in nilfs_ioctl_mark_blocks_dirty()

In the Linux kernel, the following vulnerability has been resolved: nilfs2: reject zero bd_oblocknr in nilfs_ioctl_mark_blocks_dirty() nilfs_ioctl_mark_blocks_dirty() uses bd_oblocknr to detect dead blocks by comparing it with the current block number bd_blocknr. If they differ, the block is considered dead and skipped. However, bd_oblocknr should never be 0 since block 0 typically stores the primary superblock and is never a valid GC target block. A corrupted ioctl request with bd_oblocknr set to 0 causes the comparison to incorrectly match when the lookup returns -ENOENT and sets bd_blocknr to 0, bypassing the dead block check and calling nilfs_bmap_mark() on a non-existent block. This causes nilfs_btree_do_lookup() to return -ENOENT, triggering the WARN_ON(ret == -ENOENT). Fix this by rejecting ioctl requests with bd_oblocknr set to 0 at the beginning of each iteration. [ryusuke: slightly modified the commit message and comments for accuracy]

Published: 2026-06-26 Last update: 2026-06-30 Assigner: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

Conclusion & alert: CVE-2026-53320 is rated Low Risk (6.9/100): low exploitation likelihood (EPSS 0.17%). Mandatory action: Low composite risk—no urgent action required; patch on your normal maintenance cycle and revisit priority if CVSS or EPSS increases.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-53320

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-27 0.17%

Full EPSS history (1 record total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-53320

CVSS metrics for this CVE.

No CVSS data in dataset for this CVE.

Weakness enumeration for CVE-2026-53320

GitHub Security Advisory for CVE-2026-53320

GHSA-r88h-63mh-cc6h · Severity: unknown — In the Linux kernel, the following vulnerability has been resolved: nilfs2: reject zero...

OS Trackers for CVE-2026-53320

vendor priority summary link
debian not yet assigned CVE-2026-53320 not yet assigned priority: Debian including 1 source packages (linux), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 3, open 2. https://security-tracker.debian.org/tracker/CVE-2026-53320
suse medium https://www.suse.com/security/cve/CVE-2026-53320/
ubuntu medium CVE-2026-53320 medium priority: Ubuntu including 161 source packages (linux, linux-allwinner-5.19, …), 1449 status rows across 9 suites (bionic, focal, jammy, noble, questing, resolute, trusty, upstream, xenial): DNE 1045, ignored 176, needed 124, released 87, pending 14, needs-triage 3. https://ubuntu.com/security/CVE-2026-53320

Affected software / configurations for CVE-2026-53320

Vendor Product Version Raw CPE
linux linux_kernel >= 2.6.30, < 5.10.258 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 2.6.30, < 5.15.209 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 2.6.30, < 6.1.175 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 2.6.30, < 6.6.141 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 2.6.30, < 6.12.91 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 2.6.30, < 6.18.33 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 2.6.30, < 7.0.10 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 2.6.30, < 7.1 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

References for CVE-2026-53320

cvelogic Threat Intelligence