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NVD / CVE Program· CNA Linux

CVE-2026-72379: fs: refuse O_TMPFILE creation with an unmapped fsuid or fsgid

Noroxi assessment

Priority: Monitor (action score 0/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.21% (FIRST EPSS).
  • Fixed version: Linux Linux 47e434da476b5a8bcd1e6e52ab03c5ee7764ee78, 503d0568a525b168d9aa5ca046ec72fc5477df84, 539dce1144651f7976fa418e618b0b574bf15eeb.

Low priority for now. Upgrade to Linux Linux 47e434da476b5a8bcd1e6e52ab03c5ee7764ee78, 503d0568a525b168d9aa5ca046ec72fc5477df84, 539dce1144651f7976fa418e618b0b574bf15eeb or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: fs: refuse O_TMPFILE creation with an unmapped fsuid or fsgid vfs_tmpfile() never checked that the caller's fsuid and fsgid map into the filesystem. On an idmapped mount whose idmapping does not cover the caller's fs{u,g}id, the ->tmpfile() instance initializes the new inode through inode_init_owner(), where mapped_fsuid()/mapped_fsgid() return INVALID_UID/INVALID_GID, and the tmpfile ends up owned by (uid_t)-1. Every other creation path already refuses this: may_o_create() (O_CREAT) and may_create_dentry() (mkdir, mknod, symlink, link) bail out with -EOVERFLOW via fsuidgid_has_mapping() precisely so that an object cannot be created with an owner the filesystem cannot represent. An O_TMPFILE is no exception: it is created I_LINKABLE and linkat(2) can splice it into the namespace afterwards, so the same guarantee must hold. Add the missing fsuidgid_has_mapping() check to vfs_tmpfile(). On a non-idmapped mount the caller's fs{u,g}id always map in the superblock's user namespace, so this is a no-op there and only takes effect on an idmapped mount that does not map the caller. It applies to every filesystem that sets FS_ALLOW_IDMAP and implements ->tmpfile() (tmpfs, ext4, btrfs, xfs, f2fs, ...), and to overlayfs, whose upper-layer tmpfile creation funnels through vfs_tmpfile() via backing_tmpfile_open().

—No exploit Fix available
Published
Aug 15, 2026
Updated
Oct 30, 2026
EPSS
0.2% · 11th percentile
CWE
—

Report tools

JSON

Action score

0

Monitor

Low priority for now.

CVSS
0 / 40 · —
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

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  • Not in KEV: no record of exploitation in the wild
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  • A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 5.13affected
    • 8e5389132ab429604c1a2459b52f0c849a71cc61 and later · before 74365c6e367725728d5ce36d38ca116c9f77a254affected · git
    • 8e5389132ab429604c1a2459b52f0c849a71cc61 and later · before bac8fb0d60254846f3b56957435dcd870ae12948affected · git
    • 8e5389132ab429604c1a2459b52f0c849a71cc61 and later · before 503d0568a525b168d9aa5ca046ec72fc5477df84affected · git
    • 8e5389132ab429604c1a2459b52f0c849a71cc61 and later · before a2038514e69371eb493083a6a897ed20fcbb8acbaffected · git
    • 8e5389132ab429604c1a2459b52f0c849a71cc61 and later · before 47e434da476b5a8bcd1e6e52ab03c5ee7764ee78affected · git
    • 8e5389132ab429604c1a2459b52f0c849a71cc61 and later · before 539dce1144651f7976fa418e618b0b574bf15eebaffected · git
    • before 5.13not affected · semver
    • 6.1.191 and later · up to and including 6.1.*not affected · semver
    • 6.6.145 and later · up to and including 6.6.*not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxfrom 0—
Debian:13linuxbefore 6.12.100-16.12.100-1
Debian:14linuxbefore 7.1.5-17.1.5-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-72374Aug 15, 2026 · afs: Fix callback service message parsers to pass through -EAGAIN
    30Monitor
  • ← EarlierCVE-2026-72375Aug 15, 2026 · afs: Fix reinitialisation of the inode, in particular ->lock_work
    31Monitor
  • Later →CVE-2026-72380Aug 15, 2026 · xen/pvcalls: bound backend response req_id before indexing rsp[]
    35Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux47e434da476b5a8bcd1e6e52ab03c5ee7764ee78Vendor (CNA)
Linux Linux503d0568a525b168d9aa5ca046ec72fc5477df84Vendor (CNA)
Linux Linux539dce1144651f7976fa418e618b0b574bf15eebVendor (CNA)
Linux Linux74365c6e367725728d5ce36d38ca116c9f77a254Vendor (CNA)
Linux Linuxa2038514e69371eb493083a6a897ed20fcbb8acbVendor (CNA)
Linux Linuxbac8fb0d60254846f3b56957435dcd870ae12948Vendor (CNA)
debian:linux6.12.100-1 · Debian:13Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

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Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

No CVSS vector for this record, so attack conditions can't be derived.

Weakness class (CWE)

—

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

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References

Show all references (5 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

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