Summary
uutils coreutils: cp/install/mv/ln --suffix alone does not enable backup mode (silent data loss vs GNU)
determine_backup_mode in src/uucore/src/lib/features/backup_control.rs only checks --backup/-b and returns BackupMode::None when only --suffix is given. GNU enables backup mode when --suffix is used alone (defaulting to existing/numbered, or $VERSION_CONTROL). Affects cp, install, mv, ln which share this code.
# uutils: no backup created
$ coreutils cp --suffix=.bak src dest # dest.bak NOT created
# GNU: dest.bak created
$ cp --suffix=.bak src dest
Impact: users/scripts relying on --suffix to back up a file before overwrite get silent data loss; breaks GNU compatibility across four utilities. Recommendation: enable backup mode when --suffix is present.
Note: this is primarily a GNU-compatibility/data-safety divergence rather than a classic exploitable vulnerability, review whether it warrants a CVE.
Remediation: Acknowledged by Canonical; fixed in PR #9741 (uucore: use --suffix to enable backup mode), commit 939ab037a, merged 2025-12-21. determine_backup_mode now has a --suffix-alone branch that resolves the mode from $VERSION_CONTROL (defaulting to existing). Released in uucore 0.6.0 and later (vulnerable: < 0.6.0). Regression tests added in the same file: test_backup_mode_suffix_without_backup_option and test_backup_mode_suffix_without_backup_option_with_env_var.
Reported by Zellic in the uutils coreutils Program Security Assessment (prepared for Canonical, Jan 20 2026), audited commit 3a07ffc5a9bd4c283e75afa548ba1f1957bad242. Finding 3.7. Credit: Zellic.
Impact
Affected versions
Security releases
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Frequently Asked Questions
- What is GHSA-FQF6-GXHH-2XHW? GHSA-FQF6-GXHH-2XHW is a high-severity security vulnerability in uucore (rust), affecting versions < 0.6.0. It is fixed in 0.6.0.
- Which versions of uucore are affected by GHSA-FQF6-GXHH-2XHW? uucore (rust) versions < 0.6.0 is affected.
- Is there a fix for GHSA-FQF6-GXHH-2XHW? Yes. GHSA-FQF6-GXHH-2XHW is fixed in 0.6.0. Upgrade to this version or later.
- Is GHSA-FQF6-GXHH-2XHW exploitable, and should I be worried? Whether GHSA-FQF6-GXHH-2XHW is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether GHSA-FQF6-GXHH-2XHW is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix GHSA-FQF6-GXHH-2XHW? Upgrade
uucoreto 0.6.0 or later.