GHSA-239G-2685-54X3

Vulnerability from github – Published: 2026-07-06 19:54 – Updated: 2026-07-06 19:54
VLAI
Summary
install: TOCTOU symlink race (unlink-then-create without O_EXCL) allows arbitrary file overwrite
Details

copy_file in install/src/install.rs removes the destination then recreates it by pathname via File::create / fs::copy without O_EXCL/create_new. Between the unlink and the recreate, a local attacker with write access to the destination directory can drop in a symlink and redirect the write.

Impact: when install runs privileged into an attacker-writable directory (staging/build paths), the race allows redirecting writes to arbitrary files and overwriting sensitive system files (/etc/passwd, /etc/shadow). Recommendation: create atomically with create_new/O_EXCL and copy via the opened fd rather than reopening by path.

Remediation: Acknowledged by Canonical; fixed in commit b5bbabc1.

Reported by Zellic in the uutils coreutils Program Security Assessment (prepared for Canonical, Jan 20 2026), audited commit 3a07ffc5a9bd4c283e75afa548ba1f1957bad242. Finding 3.50. Credit: Zellic.

Severity
6.3 (Medium)
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:H
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{
  "affected": [
    {
      "package": {
        "ecosystem": "crates.io",
        "name": "uu_install"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.6.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-35355"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-367",
      "CWE-59"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-06T19:54:08Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "`copy_file` in `install/src/install.rs` removes the destination then recreates it by pathname via `File::create` / `fs::copy` without `O_EXCL`/`create_new`. Between the unlink and the recreate, a local attacker with write access to the destination directory can drop in a symlink and redirect the write.\n\n**Impact:** when `install` runs privileged into an attacker-writable directory (staging/build paths), the race allows redirecting writes to arbitrary files and overwriting sensitive system files (`/etc/passwd`, `/etc/shadow`). Recommendation: create atomically with `create_new`/`O_EXCL` and copy via the opened fd rather than reopening by path.\n\n**Remediation:** Acknowledged by Canonical; fixed in commit b5bbabc1.\n\n---\n_Reported by Zellic in the *uutils coreutils Program Security Assessment* (prepared for Canonical, Jan 20 2026), audited commit `3a07ffc5a9bd4c283e75afa548ba1f1957bad242`. Finding 3.50. Credit: Zellic._",
  "id": "GHSA-239g-2685-54x3",
  "modified": "2026-07-06T19:54:08Z",
  "published": "2026-07-06T19:54:08Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/uutils/coreutils/security/advisories/GHSA-239g-2685-54x3"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-35355"
    },
    {
      "type": "WEB",
      "url": "https://github.com/uutils/coreutils/pull/10067"
    },
    {
      "type": "WEB",
      "url": "https://github.com/uutils/coreutils/commit/b5bbabc18a1121908848d836f869a4e98eb63886"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/uutils/coreutils"
    },
    {
      "type": "WEB",
      "url": "https://github.com/uutils/coreutils/releases/tag/0.6.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "install: TOCTOU symlink race (unlink-then-create without O_EXCL) allows arbitrary file overwrite"
}



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