CVE-2026-54557 — mise
MEDIUMCVE-2026-54557 is a medium-severity (CVSS 5.5) Path Traversal vulnerability in mise. A fix is available for mise — see the affected versions and patch details below.
mise HTTP backend uses raw version path for install symlink destination
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-54557.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-54557 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,166 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
miseReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.
Description
mise manages dev tools like node, python, cmake, and terraform. Prior to 2026.6.1, the mise HTTP backend builds its install symlink destination from the raw resolved version string for non-latest versions. Normal tool install paths use the sanitized version pathname, but the HTTP backend's symlink path uses the raw value. On Unix-like systems, if that version is an absolute path, PathBuf::join discards the intended mise installs root. A repository-controlled .tool-versions file can therefore make mise install create a symlink outside the mise install tree. With bin_path, the same issue can place an executable symlink under an attacker-selected absolute prefix, such as a developer-tool prefix that is later added to PATH. This vulnerability is fixed in 2026.6.1.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | mise | all versions | 2026.6.1cargo update -p mise --precise 2026.6.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mise, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update mise to 2026.6.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-54557 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-54557 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-54557. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-54557 in your dependencies?
O3 Security finds CVE-2026-54557 across crates.io dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.