constructor: Authentication Bypass by Alternate Name
CVE-2025-64343 is a high-severity authentication bypass by alternate name vulnerability in constructor from Conda, with a CVSS 3.1 base score of 7.8 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 constructor versions: < 3.13.0. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.13% 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 constructor 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
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Conda | constructor | < 3.13.0 | Not stated |
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
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (github.com).
Official description
(conda) Constructor is a tool that enables users to create installers for conda package collections. In versions 3.12.2 and below, the installation directory inherits permissions from its parent directory. Outside of restricted directories, the permissions are very permissive and often allow write access by authenticated users. Any logged in user can make modifications during the installation for both single-user and all-user installations. This constitutes a local attack vector if the installation is in a directory local users have access to. For single-user installations in a shared directory, these permissions persist after the installation. This issue is fixed in version 3.13.0.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Authentication Bypass by Alternate Name
The product performs authentication based on the name of a resource being accessed, or the name of the actor performing the access, but it does not properly check all possible names for that resource or actor.
How developers prevent this class of flaw
- Avoid making decisions based on names of resources (e.g. files) if those resources can have alternate names.
- 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 Authentication Bypass by Alternate Name vulnerabilities (CWE-289)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Recent Authentication Bypass by Alternate Name vulnerabilities
- 7.5 High severity
- 9.6 Critical severity
- 7.5 High severity
- 9.8 Critical severity
- 7.5 High severity
- 8.2 High severity
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