CVE-2026-35342: mktemp Empty TMPDIR Creates Temp Files Vulnerability

LOW
Advisory Identifier: GHSA-2w8r-9xj7-69j5
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CVSS 3.3
CWE-377
Published
Advisory Summary

CVE-2026-35342 is a LOW (CVSS 3.3) empty tmpdir creates temp files vulnerability (CWE-377: Insecure Temporary File) affecting mktemp libraries in the crates.io ecosystem. The issue involves empty tmpdir creates temp files in cwd instead of /tmp. Remediation is available by upgrading affected packages to version 0.6.0.

CVE-2026-35342 at a Glance

CVE Identifier CVE-2026-35342
GHSA Identifier GHSA-2w8r-9xj7-69j5
Severity LOW
CVSS v3.1 Base Score 3.3
CWE Classification CWE-377: Insecure Temporary File
Affected Product mktemp
Package Ecosystem crates.io
Published Date
Last Updated

Security Impact

CVSS: 3.3

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N).

Attack Vector Local (AV:L)
Attack Complexity Low (AC:L)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality Low (C:L)
Integrity None (I:N)
Availability None (A:N)

How to Fix CVE-2026-35342

To remediate this vulnerability, upgrade all affected mktemp dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

uu_mktemp fixed: 0.6.0 
Upgrade uu_mktemp to 0.6.0
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for uu_mktemp

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-35342, inspect your project dependencies for mktemp:

inspect dependencies for uu_mktemp

Analyze the terminal output to locate any version of mktemp in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.6.0), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-377: Insecure Temporary File, where creating and using insecure temporary files can leave application and system data vulnerable to attack. In mktemp, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

The mktemp utility in uutils coreutils fails to properly handle an empty TMPDIR environment variable. Unlike GNU mktemp, which falls back to /tmp when TMPDIR is an empty string, the uutils implementation treats the empty string as a valid path. This causes temporary files to be created in the current working directory (CWD) instead of the intended secure temporary directory. If the CWD is more permissive or accessible to other users than /tmp, it may lead to unintended information disclosure or unauthorized access to temporary data. --- _Zellic finding 3.11. Reported in the Zellic *uutils coreutils Program Security Assessment* (for Canonical, Jan 2026), audited commit `3a07ffc5a9bd4c283e75afa548ba1f1957bad242`._

CVE-2026-35342 Affected mktemp Versions

1 component(s)
Fixed Versions:
0.6.0
Product / Package Ecosystem Affected Versions Fixed Version
uu_mktemp
 crates.io
< 0.6.0
0.6.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/uutils/coreutils/security/advisories/GHSA-2w8r-9xj7-69j5
NVD — CVE-2026-35342 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-35342
mktemp Source Repository REPOSITORY
https://github.com/uutils/coreutils/pull/10566
Security Fix Commit FIX COMMIT
https://github.com/uutils/coreutils/commit/eb25ec328b226d8fbbaa4058bf9187165bf06d51
mktemp Source Repository REPOSITORY
https://github.com/uutils/coreutils
mktemp Release RELEASE
https://github.com/uutils/coreutils/releases/tag/0.6.0

Frequently Asked Questions

What is CVE-2026-35342?
CVE-2026-35342 is a security vulnerability in mktemp involving empty TMPDIR creates temp files in CWD instead of /tmp under CWE-377: Insecure Temporary File.
Which mktemp versions are affected?
Affected versions include releases prior to 0.6.0 across affected packages: uu_mktemp.
What version fixes CVE-2026-35342?
Upgrading to 0.6.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is uu_mktemp affected?
Yes, uu_mktemp is affected in releases prior to 0.6.0. Upgrade your dependency to 0.6.0 or later.
What is the CVSS score of CVE-2026-35342?
CVE-2026-35342 has a CVSS v3.1 base score of 3.3 (LOW) with vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N.
What CWE is associated with CVE-2026-35342?
CVE-2026-35342 is classified under CWE-377: Insecure Temporary File (Creating and using insecure temporary files can leave application and system data vulnerable to attack.).
How can I check crates.io dependencies for CVE-2026-35342?
Run the dependency tree command: 'inspect dependencies for uu_mktemp'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-2w8r-9xj7-69j5",
  "modified" : "2026-07-06T19:50:41Z",
  "published" : "2026-07-06T19:50:41Z",
  "aliases" : [ "CVE-2026-35342" ],
  "summary" : "mktemp: empty TMPDIR creates temp files in CWD instead of /tmp",
  "details" : "The mktemp utility in uutils coreutils fails to properly handle an empty TMPDIR environment variable. Unlike GNU mktemp, which falls back to /tmp when TMPDIR is an empty string, the uutils implementation treats the empty string as a valid path. This causes temporary files to be created in the current working directory (CWD) instead of the intended secure temporary directory. If the CWD is more permissive or accessible to other users than /tmp, it may lead to unintended information disclosure or unauthorized access to temporary data.\n\n---\n_Zellic finding 3.11. Reported in the Zellic *uutils coreutils Program Security Assessment* (for Canonical, Jan 2026), audited commit `3a07ffc5a9bd4c283e75afa548ba1f1957bad242`._",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "uu_mktemp"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.6.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/uutils/coreutils/security/advisories/GHSA-2w8r-9xj7-69j5"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-35342"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/uutils/coreutils/pull/10566"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/uutils/coreutils/commit/eb25ec328b226d8fbbaa4058bf9187165bf06d51"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/uutils/coreutils"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/uutils/coreutils/releases/tag/0.6.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-377" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-06T19:50:41Z",
    "nvd_published_at" : null
  }
}