GHSA-85g2-pmrx-r49q CVE-2026-46617 GO-2026-5241
Fission runtime pods automount the fission-fetcher service-account token into the user function container, granting function code namespace-wide secret / configmap read
- Severity
- 0.0 / 10
- High · CVSS 4.0
- Exploit chance (EPSS)
- 0.35%
- Chance of exploitation in the next 30 days. Higher than 28.19% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-250 Execution with Unnecessary Privileges
- CWE-269 Improper Privilege Management
- CWE-538 Insertion of Sensitive Information into Externally-Accessible File or Directory
- Fix
1.23.0- Upgrade github.com/fission/fission to this version or later
Description
Summary
Fission runtime pods were created with ServiceAccountName: fission-fetcher, and the fission-fetcher ServiceAccount was granted namespace-wide get on secrets and configmaps (it needs that to load function code, env vars, and config). The runtime pod's automounted token was reachable from inside the user's function container at /var/run/secrets/kubernetes.io/serviceaccount/token, so user-supplied function code inherited the same Kubernetes API privileges and could read any secret or configmap in the function's namespace — far beyond the Function.spec.secrets allowlist that the function specification suggests.
Affected component
pkg/executor/executortype/poolmgr/gp_deployment.go:154-156— pool-manager runtime podServiceAccountName.pkg/executor/executortype/newdeploy/newdeploy.go:225-227— new-deploy runtime podServiceAccountName.pkg/utils/serviceaccount.go:51-64—fission-fetcherRBAC: namespace-widegetonsecrets/configmaps.
Impact
A user able to deploy or update a function in any namespace where Fission runtime pods are scheduled could:
- Read every secret in that namespace (TLS keys, OIDC client secrets, database credentials, cloud provider credentials).
- Read every configmap in that namespace.
- Use those credentials to pivot to other Kubernetes resources or external systems the secrets unlock.
This violates the principle that Function.spec.secrets is the authoritative declaration of which secrets a function can read.
Root cause
The fetcher sidecar legitimately needs the SA token to call the Fission control plane and fetch package archives. Setting ServiceAccountName: fission-fetcher on the pod gives every container in the pod (including the user container) the automounted token. Kubernetes does not provide per-container service-account scoping inside a single pod, so the user container has to be moved into a separate identity / token-mount scheme.
Fix
Released in v1.23.0:
- PR #3366 (commit
fe1842ef):- The user function container now sets
AutomountServiceAccountToken: falseat the container level (via projected-volume token suppression), so the user container no longer sees the pod's SA token even though the fetcher sidecar still does. - The fetcher sidecar retains its existing token mount (separate projected volume) since it needs cluster API access for its own work.
- For the few legitimate use cases where a function needs its own Kubernetes API access, the user is expected to mount a different ServiceAccount via
Function.spec.podspecwith the minimum necessary RBAC (documented separately).
- The user function container now sets
Mitigation (until upgrade)
- Restrict who can create / update
FunctionandPackageCRDs in your cluster — treat the ability to ship function code as equivalent to namespace-wide secret read. - Reduce the
fission-fetcherClusterRole / Role scope where possible (e.g. constrain it to specific named secrets via separate Role bindings). - Add NetworkPolicy egress rules denying function pods access to the Kubernetes API server (this blunts the token even if it leaks).
Affected versions
Go
| Package | Vulnerable | Fixed in |
|---|---|---|
| github.com/fission/fission | < 1.23.0 |
1.23.0 |
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 → 1.23.0
- go
go get github.com/fission/fission@v1.23.0 && go mod tidy
Severity breakdown
CVSS 4.0 0.0
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
- Attack vector
- Network
- Attack complexity
- Low
- Attack requirements
- None
- Privileges required
- None
- User interaction
- None
- Confidentiality (vulnerable system)
- High
- Integrity (vulnerable system)
- None
- Availability (vulnerable system)
- None
- Confidentiality (subsequent systems)
- None
- Integrity (subsequent systems)
- None
- Availability (subsequent systems)
- None
Weakness
CWE-250: Execution with Unnecessary Privileges
The product performs an operation at a privilege level that is higher than the minimum level required, which creates new weaknesses or amplifies the consequences of other weaknesses.
How to prevent it
- 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: Identify the functionality that requires additional privileges, such as access to privileged operating system resources. Wrap and centralize this functionality if possible, and isolate the privileged code as much as possible from other code [REF-76]. Raise privileges as late as possible, and drop them as soon as possible to avoid CWE-271. Avoid weaknesses such as CWE-288 and CWE-420 by protecting all possible communication channels that could interact with the privileged code, such as a secondary socket that is only intended to be accessed by administrators.
- Architecture and Design: Identify the functionality that requires additional privileges, such as access to privileged operating system resources. Wrap and centralize this functionality if possible, and isolate the privileged code as much as possible from other code [REF-76]. Raise privileges as late as possible, and drop them as soon as possible to avoid CWE-271. Avoid weaknesses such as CWE-288 and CWE-420 by protecting all possible communication channels that could interact with the privileged code, such as a secondary socket that is only intended to be accessed by administrators.
- Implementation: Perform extensive input validation for any privileged code that must be exposed to the user and reject anything that does not fit your strict requirements.
- Implementation: When dropping privileges, ensure that they have been dropped successfully to avoid CWE-273. As protection mechanisms in the environment get stronger, privilege-dropping calls may fail even if it seems like they would always succeed.
- Implementation: If circumstances force you to run with extra privileges, then determine the minimum access level necessary. First identify the different permissions that the software and its users will need to perform their actions, such as file read and write permissions, network socket permissions, and so forth. Then explicitly allow those actions while denying all else [REF-76]. Perform extensive input validation and canonicalization to minimize the chances of introducing a separate vulnerability. This mitigation is much more prone to error than dropping the privileges in the first place.
- Operation, System Configuration: Ensure that the software runs properly under the United States Government Configuration Baseline (USGCB) [REF-199] or an equivalent hardening configuration guide, which many organizations use to limit the attack surface and potential risk of deployed software.
CWE-269: Improper Privilege Management
The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that 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: Follow the principle of least privilege when assigning access rights to entities in a software system.
- Architecture and Design: Consider following the principle of separation of privilege. Require multiple conditions to be met before permitting access to a system resource.
CWE-538: Insertion of Sensitive Information into Externally-Accessible File or Directory
The product places sensitive information into files or directories that are accessible to actors who are allowed to have access to the files, but not to the sensitive information.
How to prevent it
- Architecture and Design, Operation, System Configuration: Do not expose file and directory information to the user.
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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