sdk: Improper Limitation of a Pathname to a Restricted Directory
CVE-2026-27704 is a high-severity improper limitation of a pathname to a restricted directory vulnerability in sdk from Dart-lang, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected sdk versions: < 3.11.0. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.41% 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
- Update Dart Software Development Kit to 3.11.0 or a later version.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Dart-lang | sdk | < 3.11.0 | Not stated |
| Dart-lang | flutter | < 3.41.0 | Not stated |
| Dart | Dart Software Development Kit | before 3.11.0 | 3.11.0 |
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
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- NoneNothing can be modified.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 6.6 | Medium | CNA (github.com) |
| CVSS 3.1 | 7.5 | High | NVD |
Official description
The Dart and Flutter SDKs provide software development kits for the Dart programming language. In versions of the Dart SDK prior to 3.11.0 and the Flutter SDK prior to version 3.41.0, when the pub client (`dart pub` and `flutter pub`) extracts a package in the pub cache, a malicious package archive can have files extracted outside the destination directory in the `PUB_CACHE`. A fix has been landed in commit 26c6985c742593d081f8b58450f463a584a4203a. By normalizing the file path before writing file, the attacker can no longer traverse up via a symlink. This patch is released in Dart 3.11.0 and Flutter 3.41.0.vAll packages on pub.dev have been vetted for this vulnerability. New packages are no longer allowed to contain symlinks. The pub client itself doesn't upload symlinks, but duplicates the linked entry, and has been doing this for years. Those whose dependencies are all from pub.dev, third-party repositories trusted to not contain malicious code, or git dependencies are not affected by this vulnerability.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Limitation of a Pathname to a Restricted Directory
The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.
How developers prevent this class of flaw
- For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
- Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth.
More Improper Limitation of a Pathname to a Restricted Directory vulnerabilities (CWE-22)
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
Patches and release notes
Recent Improper Limitation of a Pathname to a Restricted Directory vulnerabilities
- 7.2 High severity
- 8.8 High severity
- 9.8 Critical severity
- 9.1 Critical severity
- 8.1 High severity
- 9.3 Critical severity
Spotted an error? Tell us.