deno: Improper Resolution of Path Equivalence
CVE-2026-49401 is a high-severity improper resolution of path equivalence vulnerability in deno from Denoland, with a CVSS 3.1 base score of 8.4 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. Affected deno versions: < 2.7.14. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.2% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of deno you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on github.com for workarounds and exact fixed builds.
Affected products and versions
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.3 | High | CNA (github.com) |
| CVSS 3.1 | 8.4 | High | NVD |
Official description
Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.7.14, 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. This vulnerability is fixed in 2.7.14.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Resolution of Path Equivalence
The product is vulnerable to file system contents disclosure through path equivalence. Path equivalence involves the use of special characters in file and directory names. The associated manipulations are intended to generate multiple names for the same object.
How developers prevent this class of flaw
- Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.
More Improper Resolution of Path Equivalence vulnerabilities (CWE-41)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Advisories
- github.com/denoland/deno/security/advisories/GHSA-8xpq-cjcf-3wh9Exploit, Mitigation
Other vulnerabilities in deno
- 8.1 High severity
- 7.4 High severity
- 8.1 High severity
- 9.1 Critical severity
- 9.8 Critical severity
- 9.8 Critical severity
Recent Improper Resolution of Path Equivalence vulnerabilities
- 8.1 High severity
- 7.8 High severity
- 7.3 High severity
- 8.6 High severity
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