CVE-2026-108126: temporal-proxy payload decryption is not bound to the request namespace
temporal-proxy 0.2.0 through 0.8.0 does not bind encrypted payloads to the namespace they were encrypted for. When payload encryption is enabled, the proxy chooses the decryption key by an identifier stored in the payload rather than by the namespace of the request, and nothing in the ciphertext records that namespace. A caller whom the proxy authorizes only for namespace B, and who has obtained an encrypted payload from namespace A, can therefore have the proxy decrypt it. In 0.8.0, the caller can submit the payload to the codec server's /decode endpoint. In every affected version, a caller who can also write to namespace B on the Temporal server directly can place the payload there and read it back through the proxy. This holds whether namespaces share the default key or each has its own, because a single proxy holds every key it is configured with. The issue does not give the attacker encrypted payloads they could not already obtain, and does not allow encrypted payloads to be modified.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
temporal-proxyto a version that resolves this vulnerability.Fixed in 0.9.0 - Configuration
Set encryption.namespaceBinding to strict. If migrating payloads encrypted by earlier releases, move from off or permissive to strict only after vault_unbound_opens_total and vault_namespace_mismatches_total have remained at zero for longer than namespace retention.
temporal-proxy encryption.namespaceBinding = strict
Event History
Frequently Asked Questions
Which deployments are affected?
Temporal-proxy versions 0.2.0 through 0.8.0 are affected when payload encryption is enabled. The issue applies whether namespaces use the default shared key or separate keys, because one proxy has access to all configured keys.
What access does an attacker need to decrypt data from another namespace?
The attacker must already be authorized to use the proxy for a namespace and must have obtained an encrypted payload from another namespace. In version 0.8.0, they can submit that payload to the codec server's /decode endpoint; in all affected versions, they also need direct Temporal write access to their authorized namespace to store the payload there and retrieve it through the proxy.
Does this let an attacker obtain or alter encrypted payloads?
No. The issue does not provide access to encrypted payloads the attacker could not already obtain, and it does not allow ciphertexts to be modified.