CVE-2026-49822: Fission: Cross-namespace event leakage via KubernetesWatchTrigger allows persistent tenant surveillance
Fission is an open-source, Kubernetes-native serverless framework that simplifies the deployment of functions and applications on Kubernetes. Prior to version 1.24.0, a low-privilege developer who could create a KubernetesWatchTrigger (KWT) in their own namespace was able to establish a persistent surveillance channel over any other namespace. This issue has been patched in version 1.24.0.
Metrics
- CVSS v3.1
- 7.7
- Severity
- HIGH
- Fixed in
- —
- Affected Products
- 1
HarborGuard Analysis
Synopsis
This is an authorization bypass (cross-namespace data leakage) in Fission, the open-source Kubernetes-native serverless framework, affecting versions before 1.24.0. An authenticated low-privilege developer who can create a KubernetesWatchTrigger (KWT) resource in their own namespace can exploit the flaw over the network without any additional interaction, establishing a persistent watch channel over Kubernetes events in namespaces they have no legitimate access to. Successful exploitation gives the attacker continuous read access to event streams from arbitrary namespaces, enabling persistent tenant surveillance across a shared cluster. HarborGuard is tracking this advisory and will make a patched-image rebuild available as soon as an upstream fix version is published.
HarborGuard Coverage
Detection of CVE-2026-49822 is available across every HarborGuard environment: the CVE is ingested from upstream advisory feeds within minutes of publication and matched against all customer images, including custom-built Fission images, in connected registries and CI/CD pipelines. Any image carrying a Fission build below 1.24.0 is flagged automatically.
AvailableTriage is available using the CVSS v3.1 score of 7.7 (HIGH), with per-environment compliance policy weighting applied to escalate or suppress findings based on each customer org's configured thresholds. Routed findings are delivered to the appropriate team inbox within the customer org based on image ownership and namespace mapping.
AvailableBecause no upstream fix version has been published yet, HarborGuard re-checks the advisory on every ingest cycle and will make a patched-image rebuild available automatically the moment upstream ships a corrected release. For customers with auto-remediation enabled, the rebuild, regression-test run, and PR against affected workloads will be triggered without manual intervention once a fix is available.
Pending upstreamExploit Conditions
- Network reachabilityRequired
The attacker must reach the Kubernetes API server over the network to create a KubernetesWatchTrigger and establish the watch channel (AV:N).
- AuthenticationRequired
A low-privilege account with permission to create KubernetesWatchTrigger resources in at least one namespace is sufficient; no admin access is needed (PR:L).
- Victim interactionNot required
No victim action is needed; the attacker sets up the watch channel independently and it persists without any other user participating (UI:N).
- Attack complexityDetail
The exploit is reliable and condition-free: no race conditions, special memory layout, or environmental timing factors are required (AC:L).
Blast Radius
- Reads Kubernetes event streams from any namespace in the cluster, including namespaces belonging to other tenants.
- Gains persistent, ongoing visibility into workload lifecycle events (pod starts, restarts, failures) across namespace boundaries.
- Observes metadata that may include service names, image tags, configuration references, and other details exposing the internal topology of co-tenant workloads.
- No data modification or service availability impact is introduced by this vulnerability.
How HarborGuard Handles This
Available on HarborGuard: CVE-2026-49822 is actively tracked with re-evaluation on every advisory ingest cycle. Because no upstream fix version exists yet, HarborGuard cannot generate a patched-image rebuild at this time, but the rebuild will become available automatically the moment a fix is published upstream. In the interim, teams running Fission on multi-tenant clusters are advised to apply Kubernetes NetworkPolicy and RBAC rules to restrict which service accounts can create KubernetesWatchTrigger resources, consider namespace-level admission controls (such as an OPA or Kyverno policy) that deny KWT creation by non-admin principals, and review existing KWT objects for unexpected cross-namespace watch targets. For customers with auto-remediation enabled, the full rebuild-and-PR flow will execute without manual action once version 1.24.0 or a later fix release is confirmed upstream.
- fission / fission< 1.24.0
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N