CVE-2026-19735
MediumCVSS 4.8Exploitation Probability (EPSS)
Low risk5th percentile - higher than 5% of all known CVEs
Summary
The RFC 6528 initial-sequence-number implementation in subsys/net/ip/tcp.c derived every TCP ISN from SHA-256(unique_key || four-tuple) plus an uptime-derived offset, where unique_key is a 128-bit secret filled once by sys_csrand_get(). The return value of that call was discarded and the once guard was latched to true even when the call failed. Because sys_csrand_get() leaves the destination buffer untouched on failure, a single failed call left unique_key as its all-zero BSS content for the remainder of the boot, with no retry, no log message and no fallback.
Risk Assessment
With an all-zero key the ISN becomes a public function of the connection four-tuple plus a device-wide time offset, allowing an off-path attacker to predict ISNs and perform blind TCP connection spoofing or blind data injection/reset. This affects devices whose entropy source errored during key generation.
Recommendation
Update to a version containing the fix that moves key generation into a single guarded helper, latches only on success, logs the error, and falls back to sys_rand32_get() instead of hashing with a known-constant key. Ensure the hardware RNG or PSA crypto is available before the first TCP connection.
Related vulnerabilities
- CVE-2026-123025Critical
An OS command injection vulnerability was discovered in the Google Cloud DNS validation module of the OPNsense os-acme-client plugin through 4.17. The DnsGcloud::prepare() method decodes the dns_gcloud_key model field and directly interpolates the gcloud_account and gcloud_project string fields into a shell command passed to proc_open() via LeUtils::run_shell_command() without validation or escaping. A remote authenticated user with privileges to issue or renew certificates through the WebGUI/API can achieve arbitrary code execution as root.
- CVE-2026-122992Critical
In G4KLX DStarGateway and F4FXL DStarGateway before 7b75de6, dstarCallsignToAPRS in APRSUtils.cpp has an integer underflow via an empty RS-MS1A sender field.
- CVE-2026-122321Critical
Kyverno 1.18.0 before 1.19.2 contains a signature verification bypass in verifyImages because cached verification results are keyed by the image reference string (such as a tag) rather than bound to the verified digest, so cache hits skip signature and attestation checks. An attacker who can submit workloads and move a registry tag can warm the cache with a signed image, repoint the tag, and have Kyverno admit the workload and use mutateDigest to pin the unverified digest.
- CVE-2026-122313Critical
Kyverno from 1.17.0 before 1.19.2 contains a privilege escalation vulnerability that allows namespace-scoped tenants to modify resources in other namespaces through NamespacedMutatingPolicy targetMatchConstraints.expression CEL output lacking namespace checks. Attackers can emit a literal target such as another tenant's RoleBinding, which the cluster-wide background controller then mutates to add attacker subjects or alter Roles, NetworkPolicies, and ConfigMaps.
- CVE-2026-122311Critical
Kyverno from 1.16.0 before 1.19.2 fails to validate path segments in the resource argument of resource.get() and resource.post(), allowing namespaced CEL policies to escape their namespace. Tenants who can create a NamespacedValidatingPolicy can insert .. segments to read and write arbitrary cluster objects using the admission controller's ServiceAccount, leading to cluster takeover.
- CVE-2026-122310Critical
Kyverno from 1.19.1 before 1.19.2 validates a Policy's context.apiCall urlPath after cleaning it but executes the raw path, whose fragment or query the Kubernetes client discards. A namespace-scoped user who can create a Policy can hide ../ segments behind # or ? to reach cluster-scoped endpoints with Kyverno's ServiceAccount, gaining cluster admin.
- CVE-2026-122304Critical
Kyverno from 1.17.0 before 1.19.2 contains an authorization bypass vulnerability that allows namespace admins to escape namespace confinement because the cleanup controller builds its context loader with a nil policy. Attackers can create a namespaced CleanupPolicy with apiCall or globalReference context entries to read cross-namespace Secrets and modify validatingwebhookconfigurations using the cleanup controller's ServiceAccount.
- CVE-2026-122303Critical
Kyverno from 1.17.0 before 1.19.2 contains an authorization bypass vulnerability that allows namespace tenants to overwrite resources in other namespaces via NamespacedMutatingPolicy mutate-existing targetMatchConstraints.expression. Attackers can return a CEL map literal fabricating a target with an attacker-chosen metadata.namespace, causing the privileged background controller to overwrite Secrets, Deployments, or policies cluster-wide.
- CVE-2026-122302Critical
Kyverno before 1.19.2 contains a privilege escalation vulnerability that allows namespace admins to create resources beyond their RBAC because generate-rule admission checks verify the controller's permissions, not the author's. Attackers can create a namespaced Policy with generate rules targeting other namespaces or cluster-scoped kinds, making the background controller create or clone resources cluster-wide.
- CVE-2026-122051Critical
A flaw was found in Edimax BR-6208AC version 1.32 in an unknown functionality of the /goform/mp file. Input manipulation can lead to command injection. The attack can be launched remotely and the exploit has been published.
Original NVD description (English source)
The RFC 6528 initial-sequence-number implementation in subsys/net/ip/tcp.c derived every TCP ISN from SHA-256(unique_key || four-tuple) plus a uptime-derived offset, where unique_key is a 128-bit secret filled once by sys_csrand_get(). The return value of that call was discarded and the once guard was latched to true even when the call failed. Because sys_csrand_get() leaves the destination buffer untouched on failure (it deliberately propagates the entropy-driver error rather than filling the buffer), a single failed call left unique_key as its all-zero BSS content for the remainder of the boot, with no retry, no log message and no fallback. A failure of the cryptographic random source is required to reach the weak state — for example -ENODEV/-EIO from the entropy driver in subsys/random/random_entropy_device.c (the in-tree comment notes that the hardware RNG "might still be gathering entropy during early boot situations"), or psa_generate_random() failing in subsys/random/random_psa.c when PSA crypto is not initialised or is backed by a Bluetooth-HCI entropy device that is not yet up. The first TCP connection is what triggers key generation, so a remote peer that reaches a listening port immediately after boot, or that can provoke a reboot, has indirect influence over whether generation coincides with that window. tcp_init_isn() is called for every passive open in tcp_conn_new() and every active open in net_tcp_connect(), so the poisoned key governs all TCP connections for that boot. With an all-zero key the ISN becomes a public function of the connection four-tuple plus a device-wide time offset. An off-path attacker can compute the hash term offline for any four-tuple and recover the shared time offset from a single observed ISN, after which the ISN the device will pick for other four-tuples is predictable. That defeats exactly the protection RFC 6528 provides: blind TCP connection spoofing against peers that trust the source address, and blind data injection into or reset of connections whose four-tuple can be guessed. Devices whose entropy source never errors were never in the weak state. The fix moves key generation into a single guarded helper that latches only on success, logs the error otherwise, and makes tcp_init_isn() fall back to sys_rand32_get() — the behaviour already used when CONFIG_NET_TCP_ISN_RFC6528 is disabled — instead of hashing with a known-constant key.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS