GHSA-33c5-9fx5-fvjm CVE-2020-8559 GO-2024-2748
Privilege Escalation in Kubernetes
Medium
Go
- Severity
- 6.8 / 10
- Medium · CVSS 3.1
- Exploit chance (EPSS)
- 6.10%
- Chance of exploitation in the next 30 days. Higher than 93.43% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-601 URL Redirection to Untrusted Site ('Open Redirect')
- Fix
- Available
- 2 packages have a fixed version
Description
The Kubernetes kube-apiserver in versions v1.6-v1.15, and versions prior to v1.16.13, v1.17.9 and v1.18.7 are vulnerable to an unvalidated redirect on proxied upgrade requests that could allow an attacker to escalate privileges from a node compromise to a full cluster compromise.
Affected versions
Go
| Package | Vulnerable | Fixed in |
|---|---|---|
| k8s.io/apimachinery | < 0.16.13 |
0.16.13 |
| k8s.io/apimachinery | >= 0.17.0, < 0.17.9 |
0.17.9 |
| k8s.io/apimachinery | >= 0.18.0, < 0.18.7 |
0.18.7 |
| k8s.io/apimachinery | < 0.16.13>= 0.17.0, < 0.17.9>= 0.18.0, < 0.18.7-rc.0 |
0.16.130.17.90.18.7-rc.0 |
| k8s.io/kubernetes | < 1.16.13 |
1.16.13 |
| k8s.io/kubernetes | >= 1.17.0, < 1.17.9 |
1.17.9 |
| k8s.io/kubernetes | >= 1.18.0, < 1.18.7 |
1.18.7 |
| k8s.io/kubernetes | < 1.16.13>= 1.17.0, < 1.17.9>= 1.18.0, < 1.18.7 |
1.16.131.17.91.18.7 |
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.
k8s.io/apimachinery Go → 0.16.13
- go
go get k8s.io/apimachinery@v0.16.13 && go mod tidy
k8s.io/kubernetes Go → 1.16.13
- go
go get k8s.io/kubernetes@v1.16.13 && go mod tidy
Severity breakdown
CVSS 3.1 6.8
CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:H
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- High
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Weakness
CWE-601: URL Redirection to Untrusted Site ('Open Redirect')
The web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a redirect.
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. Use a list of approved URLs or domains to be used for redirection.
- Architecture and Design: Use an intermediate disclaimer page that provides the user with a clear warning that they are leaving the current site. Implement a long timeout before the redirect occurs, or force the user to click on the link. Be careful to avoid XSS problems (CWE-79) when generating the disclaimer page.
- 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 "/login.asp" and ID 2 could map to "http://www.example.com/". Features such as the ESAPI AccessReferenceMap [REF-45] provide this capability.
- Architecture and Design: Ensure that no externally-supplied requests are honored by requiring that all redirect requests include a unique nonce generated by the application [REF-483]. Be sure that the nonce is not predictable (CWE-330).
- Architecture and Design, Implementation: Understand all the potential areas where untrusted inputs can enter your software: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide data to the application. Remember that such inputs may be obtained indirectly through API calls. Many open redirect problems occur because the programmer assumed that certain inputs could not be modified, such as cookies and hidden form fields.
- 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].
References
Advisories
Packages
Other links
- github.com/kubernetes/kubernetes/issues/92914
- github.com/kubernetes/kubernetes/pull/92941
- bugzilla.redhat.com/show_bug.cgi
- github.com/tdwyer/CVE-2020-8559
- groups.google.com/d/msg/kubernetes-security-announce/JAIGG5yNROs/19nHQ5wkBwAJ
- groups.google.com/g/kubernetes-security-announce/c/JAIGG5yNROs
- security.netapp.com/advisory/ntap-20200810-0004
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-r6j8-c6r2-37rr kube-controller-manager is vulnerable to half-blind Server Side Request Forgery through in-tree Portworx StorageClass | Medium | Also affects k8s.io/kubernetes |
| GHSA-4x4m-3c2p-qppc Kubernetes Nodes can delete themselves by adding an OwnerReference | Medium | Also affects k8s.io/kubernetes |
| GHSA-hj2p-8wj8-pfq4 kubernetes allows nodes to bypass dynamic resource allocation authorization checks | Low | Also affects k8s.io/kubernetes |
| GO-2025-3547 Kubernetes kube-apiserver Vulnerable to Race Condition | Low | Also affects k8s.io/kubernetes |
| GHSA-3wgm-2gw2-vh5m Kubernetes GitRepo Volume Inadvertent Local Repository Access | Medium | Also affects k8s.io/kubernetes |
| GHSA-vv39-3w5q-974q Kubernetes allows Command Injection affecting Windows nodes via nodes/*/logs/query API | Medium | Also affects k8s.io/kubernetes |
| GHSA-jgfp-53c3-624w Node Denial of Service via kubelet Checkpoint API | Medium | Also affects k8s.io/kubernetes |
| GHSA-27wf-5967-98gx Kubernetes kubelet arbitrary command execution | High | Also affects k8s.io/kubernetes |
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