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CVE-2026-35355· NVD / CVE Program· CNA canonical

uutils coreutils install Arbitrary File Overwrite via Symlink TOCTOU Race

The install utility in uutils coreutils is vulnerable to a Time-of-Check to Time-of-Use (TOCTOU) race condition during file installation. The implementation unlinks an existing destination file and then recreates it using a path-based operation without the O_EXCL flag. A local attacker can exploit the window between the unlink and the subsequent creation to swap the path with a symbolic link, allowing them to redirect privileged writes to overwrite arbitrary system files.

MediumCVSS 6.3 · v3.1—No exploit Fix available
Published
Apr 22, 2026
Updated
Jun 17, 2026
EPSS
0.1% · 1th percentile
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Report tools

JSON

Action score

25

Monitor

Low priority for now.

CVSS
25 / 40 · 6.3 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
proof of concept
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · canonical
6.3
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Noroxi analysis

No Noroxi analysis for this record yet

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Affected systems

VendorProduct
uutilscoreutils

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • uutils coreutilsbefore 0.6.0

Versions reported by the vendor

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

  • Uutils coreutils

    • before 0.6.0affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
crates.iouu_installbefore 0.6.00.6.0
Debian:12rust-coreutilsall versions—
Debian:14rust-coreutilsbefore 0.6.0-10.6.0-1

Same product

uutils: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-35368uutils coreutils chroot Local Privilege Escalation and chroot Escape in via Name Service Switch (NSS) Injection
    31Monitor
  • CVE-2026-35349uutils coreutils Path-Based Safety Bypass with --preserve-root
    30Monitor
  • CVE-2026-93658uutils coreutils 0.0.18 before 0.10.0 Privilege Escalation via setuid
    29Monitor
  • CVE-2026-35338uutils coreutils chmod Path Traversal Bypass of --preserve-root
    29Monitor
  • CVE-2026-35352uutils coreutils mkfifo Privilege Escalation via TOCTOU Race Condition
    28Monitor
  • CVE-2026-35341uutils coreutils mkfifo Unauthorized Permission Change on Existing Files
    28Monitor

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
Uutils coreutils0.6.0Vendor (CNA)
crates.io:uu_install0.6.0Package registry (OSV)
debian:rust-coreutils0.6.0-1 · Debian:14Package 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.

Variant candidates

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

  • CVE-2026-353520 days apartuutils coreutils mkfifo Privilege Escalation via TOCTOU Race Condition
    28Monitor
  • CVE-2026-353560 days apartuutils coreutils install Arbitrary File Overwrite with -D via Path Component Symlink Race
    25Monitor
  • CVE-2026-353600 days apartuutils coreutils touch Arbitrary File Truncation via TOCTOU Race Condition
    25Monitor
  • CVE-2026-353640 days apartuutils coreutils mv Arbitrary File Overwrite via Cross-Device TOCTOU Race Condition
    25Monitor
  • CVE-2026-353740 days apartuutils coreutils split Arbitrary File Truncation via Time-of-Check to Time-of-Use (TOCTOU) Race Condition
    25Monitor
  • CVE-2026-353760 days apartuutils coreutils chcon Security Bypass and Mandatory Access Control (MAC) Inconsistency via TOCTOU Race Condition
    23Monitor

Chain candidates

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

—

Bug bounty scope

No known public program.

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

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • Special conditions such as timing or configuration are required.

If successful

Confidentiality
none
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
High
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-367 · Time-of-check Time-of-use (TOCTOU) Race Condition

CVSS vector

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:H

nvd-secondary

Attack context

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

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

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References

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

All records