The broker-side PushTelemetry API (KIP-714) validates only the compressed size of a client's metrics payload against telemetry.max.bytes (default 1 MB) before decompressing it. ClientTelemetryUtils.decompress() then decompresses the payload with no limit on the decompressed output size, growing a heap buffer until the compressed input is exhausted. A small, highly compressible payload (for example gzip-compressed zeros) can therefore expand to hundreds of megabytes of broker heap. Impact: An authenticated client can send a PushTelemetry request with a small compressed payload that decompresses to a very large size, consuming broker heap out of proportion to the request size. Repeated or concurrent requests can exhaust the broker heap and cause an OutOfMemoryError, degrading or crashing the broker; a client that targets multiple brokers can affect cluster availability. PushTelemetry is available to any authenticated client and is not gated by an ACL. Mitigation: Upgrade to Apache Kafka 4.2.2, 4.3.1, or 4.4.0. On affected versions there is no configuration that fully prevents the amplification, because telemetry.max.bytes bounds only the compressed size; lowering telemetry.max.bytes reduces the worst-case decompressed size proportionally and is a partial mitigation. Resolution: - From Apache Kafka 4.2.2, 4.3.1, and 4.4.0: ClientTelemetryUtils.decompress() enforces a maximum decompressed size equal to telemetry.max.bytes (default 1 MB). Decompression reads in bounded chunks and aborts with a TelemetryTooLargeException once the decompressed total exceeds the limit, so an over-large or highly compressible payload is rejected instead of being fully expanded in heap. The decompressed size is therefore bounded by default.
CVE Explorer
A Kafka broker using SASL/OAUTHBEARER with the default validator (sasl.oauthbearer.jwt.validator.class=DefaultJwtValidator) selects its implementation from configuration. When sasl.oauthbearer.jwks.endpoint.url is set, the validator verifies the JWT signature. When that URL is unset (the default) and no verification key resolver is supplied, DefaultJwtValidator silently falls back to ClientJwtValidator, which does not verify the JWT signature, algorithm, or issuer - and the broker starts with no warning or error. This is the residual of CVE-2026-33557, whose fix restored signature verification only on the path where the JWKS endpoint URL is set. Impact: A broker in this state accepts any structurally valid JWT, including "alg":"none" tokens. An unauthenticated remote attacker who can reach the listener can forge a token asserting any principal - including configured superusers - and gain full access to the cluster. Only brokers that enable SASL/OAUTHBEARER validation without a JWKS endpoint URL (and without a custom verification key resolver) are affected; brokers that set the URL verify signatures and are not affected. Unlike CVE-2026-110952 (issuer/audience not enforced by default), here no signature is verified at all. Mitigation (all affected versions, no upgrade required): Set sasl.oauthbearer.jwks.endpoint.url for every listener/mechanism that uses OAuthBearerValidatorCallbackHandler, or configure a signature-verifying sasl.oauthbearer.jwt.validator.class. Resolution: From Apache Kafka 4.2.2, 4.3.1, and 4.4.0: a broker that would fall back to the non-verifying ClientJwtValidator fails to start with a ConfigException instead of running without signature verification (secure by default).
A Kafka broker that authenticates clients with SASL/OAUTHBEARER using the bundled JWKS-backed validator always verifies the JWT signature, but two further checks are only performed when explicitly configured: - The issuer (iss) claim is verified only when sasl.oauthbearer.expected.issuer is set. When it is unset, a validly-signed token carrying the expected audience is accepted regardless of which issuer minted it. - An audience (aud) claim is required only when sasl.oauthbearer.expected.audience is set. When it is unset, a validly-signed token that omits the aud claim is accepted. (A token that carries an aud claim is still rejected when no expected audience is configured.) Both options default to unset and have been documented as optional (Importance LOW) since KIP-768 (3.1.0). Impact: The exposure is realizable mainly in deployments whose JWKS endpoint serves signing keys for more than one issuer (a multi-tenant identity provider, an aggregated/shared JWKS, or shared signing keys): a token minted for a different issuer, or a token lacking an audience, may be accepted to authenticate — potentially as a higher-privileged principal. In a single-issuer deployment where the provider controls the iss claim and issues audience-scoped tokens, exposure is limited. The signature trust anchor remains enforced in all cases. This is distinct from CVE-2026-33557 (acceptance of unsigned/unvalidated tokens); here the signature is validated and only the issuer/audience checks are not enforced by default. Mitigation (all affected versions, no upgrade required): Set both sasl.oauthbearer.expected.issuer (to your provider's exact iss value) and sasl.oauthbearer.expected.audience (to the audience(s) your brokers expect), per listener. Brokers that set these perform exact-match issuer/audience checks and are not affected. Both have been available since 3.1.0. Resolution: - From Apache Kafka 4.4.0: a broker configured with a JWKS endpoint fails to start unless both sasl.oauthbearer.expected.issuer and sasl.oauthbearer.expected.audience are set (secure by default). Deployments that intentionally do not restrict the issuer and/or audience may opt out per axis with sasl.oauthbearer.allow.unverified.issuer=true and/or sasl.oauthbearer.allow.unverified.audience=true.
An Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') vulnerability in AccessManager in Juniper Networks Session Smart Router and Session Smart Conductor allows an attacker with config-write privileges to achieve arbitrary command execution as root in the YANG configuration.
An authenticated user in Grafana can read SSO client secrets and modify instance-wide SSO settings without the required permissions (missing authorization). This affects Grafana OSS and Enterprise 13.2 installations with the experimental kubernetesSsoSettingsApi feature toggle enabled, which is disabled by default.
An Integer Underflow vulnerability in DhcpMessageDecoder in Juniper Networks Session Smart Router allows an attacker with local network access to cause information disclosure and a denial of service via a malicious DHCP reply.
An Integer Overflow vulnerability in the DPI certificate scanner in Juniper Networks Session Smart Router allows an unauthenticated remote attacker to cause a denial of service via a specially crafted TLS server certificate.
A Missing authentication for critical function vulnerability in Juniper Networks Session Smart Router allows an unauthenticated network-based attacker to obtain administrative privileges by passing crafted URL parameters to an insecure endpoint running as root. Note that this vulnerability can only be exploited prior to the device being onboarded to Mist/Conductor. The issue can no longer be exploited once a device is onboarded to Mist/Conductor.
A Stack Buffer Overflow vulnerability in the DHCP client in Juniper Networks Session Smart Router allows an unauthenticated attacker on the local network to achieve remote code execution via a malicious DHCP reply.
An Improper Limitation of a Pathname to a Restricted Directory vulnerability in ConfigDirector in Juniper Networks Session Smart Router and Session Smart Conductor allows an authenticated REST user to read, overwrite, or delete arbitrary certificate and key files on the host filesystem via the certificate and private-key REST API.
An Improper Neutralization of Special Elements used in an OS Command vulnerability in the AutomatedProvisioner in Juniper Networks Session Smart Conductor allows a remote attacker to execute arbitrary commands as root via a specially crafted salt minion ID.
An Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection') vulnerability in the web server in Juniper Networks Session Smart Router and Session Smart Conductor allows an attacker to inject arbitrary HTTP headers via unsanitized request body parameters.
An Incorrect Permission Assignment for Critical Resource vulnerability in RoutingManager in Juniper Networks Session Smart Conductor allows a local user to access sensitive routing credentials via triggering processes that write to the /tmp directory.
An Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') vulnerability in AccessManager in Juniper Networks Session Smart Router and Session Smart Conductor allows an attacker to perform arbitrary file deletion and arbitrary command execution via the deletion of an audit rule.
An Insufficient Verification of Data Authenticity vulnerability in PCLI in Juniper Networks Session Smart Router and Session Smart Conductor allows an attacker with write access to the model cache directory to execute arbitrary code and escalate privileges via the processing of unverified cache files.
An Improper Link Resolution Before File Access ('Link Following') vulnerability in the unauthenticated web server handlers in Juniper Networks Session Smart Router and Session Smart Conductor allows a local unprivileged user to overwrite arbitrary files as root via unauthenticated API endpoints. This vulnerability can be exploited on Mist-managed routers and on unmanaged Routers that have not yet been onboarded to a Conductor. Routers already managed by Conductor are not affected.
An Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection') vulnerability in the ember service in Juniper Networks Session Smart Router and Session Smart Conductor allows an attacker with local access to unmount arbitrary filesystems or cause a denial of service via the creation of specially named directories and a service restart.
An Improper Initialization vulnerability in the SSR software in Juniper Networks Session Smart Router allows an attacker to decrypt traffic or cause a denial of service via security policy assignment.
An Out-of-Bounds Read vulnerability in the VRRP implementation in Juniper Networks Session Smart Router allows an L2-adjacent attacker to read stale memory contents or cause a system fault via a specially crafted VRRPv3 advertisement.
An Out-of-Bounds Write vulnerability in the TCP header processing in Juniper Networks Session Smart Router allows an attacker to corrupt TCP payload data and potentially cause session desynchronization via a transit TCP packet with an oversized SACK option length.
An Out-of-bounds Write vulnerability in the SSR TCP proxy/optimization path in Juniper Networks Session Smart Router allows an attacker to corrupt forwarded packet data and potentially cause a data-plane crash via a transit TCP packet with a crafted TCP option length.
An Out-of-Bounds Read vulnerability in the HttpParser component in Juniper Networks Session Smart Router and Session Smart Conductor allows an attacker to cause a denial of service via a specially crafted HTTP request.
A user with permission to edit contact points but not their protected fields can change protected settings, such as a contact point's destination URL, by switching an integration to a legacy schema version, which can expose stored credentials and redirect alert notifications (incorrect authorization).
A heap buffer overflow caused by mismatched size usage in CopyArea CPU-to-FBO path in X.Org X Server before 21.1.15 and XWayland before 24.1.14 could be used by authenticated X clients to crash or potentially execute code in the X server context.
A buffer overflow in RandR ChangeProviderProperty requests in X.Org X Server before 2.1.25 and XWayland before 24.4.14 could be used by authenticated X clients to crash or execute code within the X server context.