GHSA-8xpq-cjcf-3wh9 — deno
HIGHGHSA-8xpq-cjcf-3wh9 is a high-severity (CVSS 7.3) vulnerability in deno. A fix is available for deno — see the affected versions and patch details below.
Deno: Permission Bypass via Unicode Normalization Mismatch on macOS (APFS)
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-8xpq-cjcf-3wh9.
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
GHSA-8xpq-cjcf-3wh9 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 379,145 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
denoReal-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
Summary
Deno's permission system enforces filesystem and execution restrictions by
comparing the requested path against the path supplied to --deny-read,
--deny-write, --deny-run, or --deny-ffi. On macOS, that comparison was
done at the raw-byte level while the APFS filesystem treats different Unicode
spellings of the same name as the same file.
That means a program could reach a denied path by spelling it differently than
the deny rule. For example, with --deny-read=/secrets/passwörter.txt, a
script could still read the file by opening /secrets/passwo\u0308rter.txt
(NFD instead of NFC), or /SECRETS/PASSWÖRTER.txt (different case, since
default APFS volumes are case-insensitive). Other forms include ligature
characters (fi vs fi, ff vs ff, …) and German ß vs ss.
The denied path and the requested path differed at the byte level, so Deno's
permission check passed; the kernel then resolved them to the same inode and
served the file anyway. The same flaw affected --deny-write, --deny-run,
and --deny-ffi, which share the same path-comparison code.
Am I affected?
You are potentially affected if all of the following are true:
- You run Deno on macOS (the issue is specific to APFS path-equivalence rules; Linux and Windows are not affected by this variant).
- You rely on
--deny-read,--deny-write,--deny-run, or--deny-ffias a security boundary against less-trusted code — a dependency, plugin, or attacker-controlled input. - The protected path contains characters that have alternate Unicode
spellings — most commonly accented characters (
é,ñ,ö, …), Germanß, or Latin ligatures — or you rely on case-sensitivity on a default APFS volume.
If you only run fully trusted code, or your deny rules cover paths that are pure ASCII with no case-sensitive aliases, you are not exposed to this specific bypass.
Impact
A program running with broad --allow-read (or --allow-write /
--allow-run / --allow-ffi) but with --deny-* carve-outs for specific
paths could read, write, execute, or load via FFI those denied paths by
referring to them through a Unicode- or case-equivalent spelling. The sandbox
model on macOS was weaker than the flags suggested.
Workaround
If you cannot upgrade immediately:
- Prefer
--allow-*allowlists over--deny-*denylists. Allow rules match against the original specifier, so an attacker-supplied alternate spelling will not match a path you didn't explicitly grant. - Do not rely on case-sensitivity of paths on macOS for security boundaries; default APFS volumes are case-insensitive.
Fix
On macOS, Deno now normalizes both the deny-rule path and the requested path to NFC and applies Unicode case folding before comparing them. This matches how APFS resolves paths at the inode level, so byte-different but equivalent spellings are now rejected by the same deny rule.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | deno | all versions | 2.7.14cargo update -p deno --precise 2.7.14 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for deno, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update deno to 2.7.14 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-8xpq-cjcf-3wh9 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 GHSA-8xpq-cjcf-3wh9 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-8xpq-cjcf-3wh9. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-8xpq-cjcf-3wh9 in your dependencies?
O3 Security finds GHSA-8xpq-cjcf-3wh9 across crates.io dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.