GHSA-3r8v-2xmj-5c39 CVE-2026-49823 GO-2026-5846
Fission: Cross-namespace Package read via unvalidated PackageRef in Function admission webhook
- Severity
- 7.7 / 10
- High · CVSS 3.1
- Exploit chance (EPSS)
- 0.27%
- Chance of exploitation in the next 30 days. Higher than 18.51% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Fix
1.24.0- Upgrade github.com/fission/fission to this version or later
Description
Summary
A Fission Function spec carries three reference types — Secret, ConfigMap, and Package. The first two were namespace-validated by the admission webhook; PackageRef.Namespace was not.
Details
A tenant with functions.fission.io/create in their own namespace could set spec.package.packageref.namespace to any other namespace. When the function is invoked, the fetcher sidecar reads the victim Package using the
fission-fetcher service account's namespace-wide get packages permission and writes its contents to /userfunc/deployarchive inside the attacker's pool pod, exposing the victim's source code and any embedded credentials.
The fission-fetcher SA holds get packages in every configured function namespace (granted by charts/fission-all/templates/_function-access-role.tpl), so the namespace check was the only barrier between the attacker and any
in-cluster Fission Package.
Impact
A function author in one namespace could read the deployment archive — and therefore the source code and embedded secrets — of any Package in any other namespace.
Fix
Fixed in #3389 and released in v1.24.0.
The admission webhook (pkg/webhook/function.go::Validate) rejects Function.spec.package.packageref.namespace != metadata.namespace. An empty namespace remains accepted (controllers default it to the function's namespace). This
shipped together with the EnvironmentRef cross-namespace check (GHSA-cvw6-gfvv-953q).
Behavioural change
Functions that explicitly set spec.package.packageref.namespace to a different namespace are now rejected at admission.
Affected versions
Go
| Package | Vulnerable | Fixed in |
|---|---|---|
| github.com/fission/fission | < 1.24.0 |
1.24.0 |
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/fission/fission Go → 1.24.0
- go
go get github.com/fission/fission@v1.24.0 && go mod tidy
Severity breakdown
CVSS 3.1 7.7
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- None
- Scope
- Changed
- Confidentiality
- High
- Integrity
- None
- Availability
- None
Weakness
CWE-284: Improper Access Control
The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.
How to prevent it
- Architecture and Design, Operation: Very carefully manage the setting, management, and handling of privileges. Explicitly manage trust zones in the software.
- Architecture and Design: Compartmentalize the system to have "safe" areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.
CWE-863: Incorrect Authorization
The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.
How to prevent it
- Architecture and Design: Divide the product into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully mapping roles with data and functionality. Use role-based access control (RBAC) [REF-229] to enforce the roles at the appropriate boundaries. Note that this approach may not protect against horizontal authorization, i.e., it will not protect a user from attacking others with the same role.
- Architecture and Design: Ensure that access control checks are performed related to the business logic. These checks may be different than the access control checks that are applied to more generic resources such as files, connections, processes, memory, and database records. For example, a database may restrict access for medical records to a specific database user, but each record might only be intended to be accessible to the patient and the patient's doctor [REF-7].
- 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. For example, consider using authorization frameworks such as the JAAS Authorization Framework [REF-233] and the OWASP ESAPI Access Control feature [REF-45].
- Architecture and Design: For web applications, make sure that the access control mechanism is enforced correctly at the server side on every page. Users should not be able to access any unauthorized functionality or information by simply requesting direct access to that page. One way to do this is to ensure that all pages containing sensitive information are not cached, and that all such pages restrict access to requests that are accompanied by an active and authenticated session token associated with a user who has the required permissions to access that page.
- System Configuration, Installation: Use the access control capabilities of your operating system and server environment and define your access control lists accordingly. Use a "default deny" policy when defining these ACLs.
References
Advisories
Packages
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-7m8x-qg2j-4m3v Fission: MessageQueueTrigger scaler manager materializes Secret values into Deployment envvars and accepts arbitrary user PodSpec | High | Also affects github.com/fission/fission |
| GHSA-qf5v-m7p4-95rp Fission: Incomplete capability denylist in Environment/Function PodSpec validation allows tenant-added CAP_SYS_TIME and cross-tenant node wall-clock corruption | High | Also affects github.com/fission/fission |
| GHSA-vchh-r53j-8mpw Fission: HTTPTrigger admission omits RelativeURL / Prefix validation; kubectl apply bypasses CLI checks | Medium | Also affects github.com/fission/fission |
| GHSA-r5jh-q2mw-gcx4 Fission: SanitizeFilePath lexical HasPrefix bypass permits sibling-directory escape | Low | Also affects github.com/fission/fission |
| GHSA-q6vm-xqc9-v3ff Fission: Zip Slip in pkg/utils/zip.go:Unarchive allows fetcher to write outside the destination directory | High | Also affects github.com/fission/fission |
| GHSA-m63v-2g9w-2w6v Fission: Environment Runtime.Container and Builder.Container SecurityContext bypass allows privileged pod creation | Critical | Also affects github.com/fission/fission |
| GHSA-8wcj-mfrc-jx5q Fission builder pods auto-mount the fission-builder ServiceAccount token in the user-supplied builder container | Medium | Also affects github.com/fission/fission |
| GHSA-gx55-f84r-v3r7 Fission Environment CRD podspec passthrough enables hostPID/hostNetwork/privileged pods, node escape | Critical | Also affects github.com/fission/fission |
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