eMudhra Intermediate CA Compromise (October 2026)

Status: Advisory Affected products: TrueNAS CE/Enterprise (SCALE), TrueNAS CORE, TrueCommand, TrueNAS Connect, TrueNAS app catalog, install media — see per-product applicability below Severity (TrueNAS-adjusted): Medium Upstream severity: High (trusted intermediate CA key compromise; impersonation of arbitrary TLS endpoints) External references: Debian bug #1151413; vendor ca-certificates / trust-store security updates; Mozilla, Microsoft, Apple and Chrome root-program revocations

On 20 October 2026 it was disclosed that the private keys of eight eMudhra intermediate certificate authorities were compromised. The affected intermediates chain to two roots present in the Mozilla, Microsoft, Apple and Chrome root programs and in many downstream trust stores: “emSign ECC Root CA - G3” and “AAA Certificate Services” (Comodo). An attacker in possession of one of the compromised intermediate keys can issue a valid TLS certificate for any hostname and, from a privileged network position, impersonate any service a victim connects to over TLS.

This is an external public-key-infrastructure incident. It is not a defect in any TrueNAS feature, service, or code path. It affects TrueNAS only to the extent that TrueNAS components establish outbound TLS connections and validate them against a trust store that still trusts the affected roots.

TrueNAS products validate outbound TLS connections against operating-system and runtime trust stores that, prior to remediation, include the two affected roots. Browser- and OS-level revocation mechanisms (OneCRL, CRLite, CRLSets) that protected end-user browsers on 17–19 October are not consumed by TrueNAS appliances; TrueNAS relies on its bundled trust store, so exposure persists on an affected system until that trust store is updated to distrust the compromised chain.

The outbound TLS connections that transit the system trust store include: operating-system and application updates, cloud sync and cloud backup to third-party providers, the application catalog, TrueNAS Connect, outbound mail (SMTP over TLS), ACME certificate issuance, and directory-services traffic (LDAPS) where configured.

TrueNAS is not affected in its role as a server. The certificates TrueNAS presents for the WebUI/API, SMB, NFS, iSCSI, NVMe-oF, and S3 are self-signed or administrator-provided and do not derive from the compromised intermediates. Inbound connections from storage clients and administrators are therefore not exposed by this incident. The exposure is confined to TrueNAS acting as a TLS client on connections an attacker is positioned to intercept.

• TrueNAS CE/Enterprise (SCALE): Debian-derived base. The system trust store (/etc/ssl/certs, Debian ca-certificates) trusts the affected roots until updated. On SCALE, Python certifi resolves to the system bundle, so the system update also covers middleware/Python outbound TLS. Go-based tools (cloud sync and backup) use the system certificate pool and are covered by the same bundle update; in addition, affected Go and Rust components are rebuilt against patched toolchains (Go 1.26.10 / 1.27.3 add a crypto/x509 denylist for the compromised intermediates; the equivalent is delivered via the rustls-webpki / webpki-roots crates) to cover cases where a runtime does not read the updated system store. Remediated by a TrueNAS release incorporating the updated ca-certificates and the rebuilt components.
• TrueNAS CORE: FreeBSD base. The trust store is provided by ca_root_nss. TrueNAS CORE does not receive an updated trust-store package for this incident and is not remediated by the SCALE update. Operators of CORE systems should apply a manual host trust-store mitigation (unsupported) or migrate to a supported, maintained platform.
• TrueCommand: Distributed as a separate appliance/container with its own trust store and its own outbound TLS (including connections to managed TrueNAS systems). It must be updated independently of the TrueNAS host.
• TrueNAS Connect: A TrueNAS appliance’s connection to the TrueNAS Connect service is an outbound client TLS connection and is covered by the appliance trust-store remediation described here. The TrueNAS Connect cloud service itself is operated by iX; any exposure on the service side is remediated by iX as part of its infrastructure, and customers take no action for the service side.
• Application catalog (containerized applications): Each application image ships its own trust store. Updating the TrueNAS host trust store does not update a running container. Applications that make outbound TLS connections remain exposed until their images are rebuilt or updated.
• Install media (ISO): A newly installed system carries the trust store snapshot present in the media and is exposed until its first trust-store update. Refreshed media incorporates the fix.

Exploitation requires two preconditions that must hold simultaneously:

1. The attacker possesses the private key of one of the compromised eMudhra intermediate CAs, and
2. The attacker occupies a man-in-the-middle position on the network path between the TrueNAS system and the service it is connecting to (for example, control of a gateway or DNS resolver, ARP/route manipulation on a shared segment, a rogue wireless network, or BGP interception).

The incident is not remotely exploitable from an arbitrary Internet location, and it does not provide any attack against TrueNAS’s inbound storage protocols or management interface. The affected keys are additionally being revoked across browser and OS root programs, narrowing the window in which they are useful against clients that consume revocation — which TrueNAS appliances do not, making the trust-store update the operative remediation.

In a typical deployment — a TrueNAS appliance on a trusted management network reaching the Internet through controlled infrastructure — the practical risk is low to moderate: an attacker must already hold a stolen CA key and sit on the traffic path. The risk is higher where TrueNAS outbound traffic traverses untrusted or attacker-influenced network segments. Where realized, the impact is interception or impersonation of the intercepted outbound connection (for example, exposure of credentials or data sent to an impersonated endpoint).

Primary (recommended): Install the TrueNAS release that incorporates the updated trust store once available for your product and train. This distrusts the compromised chain fleet-wide with no configuration change and no functional impact.

• CE/Enterprise (SCALE): apply the point release that bundles the updated Debian ca-certificates.
• CORE: no updated trust-store package is available for TrueNAS CORE. The affected roots can be removed only by manually modifying the host trust store (FreeBSD ca_root_nss / certctl), which is an unsupported change; migrating off CORE to a maintained platform is the durable remediation.
• TrueCommand: apply the updated TrueCommand release.
• Applications: update or rebuild application images that perform outbound TLS.

Interim mitigation for advanced operators (SCALE), pending the release update: distrust the two affected roots in the system trust store. This is a blunt measure — any legitimate certificate that also chains to these roots will fail validation — and is not recommended for general deployments.

sed -i \
  -e 's|^mozilla/emSign_ECC_Root_CA_-_G3.crt|!&|' \
  -e 's|^mozilla/Comodo_AAA_Services_root.crt|!&|' \
  /etc/ca-certificates.conf && update-ca-certificates

Note: changes written to the base operating-system trust store on an appliance are not a supported configuration surface and may not persist across a product update; apply the product release as the durable fix.

Management endpoints: Keep administrator workstations’ browsers and operating systems updated; those consume root-program revocation and are protected independently of TrueNAS.

Verification (SCALE):

dpkg-query -W -f='${Version}\n' ca-certificates
grep -E 'emSign_ECC_Root_CA_-_G3|Comodo_AAA_Services_root' /etc/ca-certificates.conf

Both root entries should be present with a leading ! (distrusted) once the fix is applied.

TrueNAS is incorporating the updated trust-store packages into forthcoming releases of the actively maintained products (TrueNAS CE/Enterprise and TrueCommand) and refreshing install media. TrueNAS CORE does not receive this update; CORE operators should follow the CORE guidance above (manual mitigation or migration). This advisory will be updated as fixed releases become available per product and train.