install: TOCTOU symlink race (unlink-then-create without O_EXCL) allows arbitrary file overwrite
`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._
beschreibt (1)
Zugehörige CVEs.
| ID | Schweregrad | ausnutzbar | ||
|---|---|---|---|---|
| CVE-2026-35355US | — | — | ||
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 des… | ||||
Referenzen
Externe Belege — Patches, Meldungen, Analysen.
- https://github.com/uutils/coreutilsPACKAGE
- https://github.com/uutils/coreutils/commit/b5bbabc18a1121908848d836f869a4e98eb63886WEB
- https://github.com/uutils/coreutils/pull/10067WEB
- https://github.com/uutils/coreutils/releases/tag/0.6.0WEB
- https://github.com/uutils/coreutils/security/advisories/GHSA-239g-2685-54x3WEB
- https://nvd.nist.gov/vuln/detail/CVE-2026-35355ADVISORY
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