IBM Instana CVE-2026-19274

Requires a shared multi-tenant Kubernetes cluster running the Instana Agent Operator (Build 1.0.303-1.0.323), where the attacker is an authenticated tenant (PR:L) with permission to create InstanaAgent custom resources in a namespace they control. The concrete trigger is creating an InstanaAgent CR whose name exactly matches the victim tenant's CR, exploiting the fact that the resulting cluster-scoped ClusterRoleBinding is keyed by bare CR name with no namespace disambiguation. Limiting factors: exploitation is meaningless in single-tenant clusters or where tenants cannot create these CRs, and the attacker must know or guess the victim's CR name; no confidentiality impact and no code execution result - impact is limited to overwriting/deleting the victim's cluster RBAC (loss of monitoring integrity/availability).

The CVSS 3.1 vector (AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:H, base 9.6) is internally consistent with the description: network-reachable Kubernetes API, low attacker privileges (an ordinary namespaced tenant), no user interaction, and a scope change (S:C) because a low-privileged actor in one security authority impacts another tenant's cluster-level authorization state. Impact is integrity (I:H - overwriting/adopting another tenant's binding) and availability (A:H - deleting the binding revokes the victim agent's cluster monitoring), with correctly assessed C:N since no data is read. There is no EPSS, KEV, or POC signal provided: this is not confirmed actively exploited and no public exploit code is identified, so the 9.6 reflects potential impact and ease of the operation rather than observed mass exploitation. The realistic prerequisite - an attacker must already be a tenant on the same shared cluster and be able to create CRs in their namespace - narrows this to multi-tenant Kubernetes environments, but within those it is a genuine priority because exploitation is trivial (create a same-named CR) and can silently blind a victim's monitoring. Any organization running Instana Agent in a shared, multi-tenant cluster should treat this as urgent and patch promptly.

A tenant with only namespace-level access on a shared multi-tenant Kubernetes cluster observes that a victim team runs an InstanaAgent CR named, say, 'instana-agent'. The attacker creates an InstanaAgent CR with the identical name in their own namespace; the operator reconciles it against the single bare-named ClusterRoleBinding, overwriting or deleting the shared object and revoking the victim agent's cluster monitoring access. No public POC is available, but the attack requires only routine CR-creation permissions.