Apicurio Registry CVE-2026-12975

The attacker must be able to submit content through Apicurio Registry's artifact-write/upload path that flows into ContentTypeUtil.isParsableXml(), and the submitted document must be XML containing a DOCTYPE with external DTD/entity references (SYSTEM identifiers) for SSRF, or nested entity definitions for DoS. Required privilege depends on deployment: artifact-write permission suffices, and crucially NO authentication is required when the registry runs in its DEFAULT configuration (anonymous writes enabled). Limiting factors that reduce real-world exposure: deployments that have enabled authentication and write-authorization raise the bar to an authenticated user (PR:L); network egress filtering on the registry host prevents the outbound fetch needed for SSRF; and because the SSRF is blind, the attacker cannot directly read fetched responses, constraining data exfiltration to inference/timing and internal-service probing. The DoS path requires no outbound connectivity and works wherever XML upload is reachable.

Signals point to a genuine, prioritizable issue but with nuance. The supplied CVSS:3.1 vector (AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:H, base 8.5) describes a low-complexity network attack needing only low privileges, with a scope change (the parser reaches systems beyond the registry) and high availability impact - consistent with blind SSRF plus DoS. Critically, the description states exploitation can be UNAUTHENTICATED when the registry runs with default configuration, which is more severe than the PR:L encoded in the vector; defenders running stock deployments should treat this closer to PR:N. Confidentiality is rated only Low because the SSRF is described as blind (the attacker drives requests but does not directly read responses), so its value is internal network pivoting/probing and service disruption rather than bulk data theft. No EPSS score, KEV listing, SSVC decision, or POC was provided: there is no evidence of active exploitation and no public exploit identified at time of analysis, so urgency rests on ease of exploitation against default configs rather than observed in-the-wild activity. Net: real priority for internet- or multi-tenant-exposed registries, especially default-config installs; lower urgency where artifact-write is authenticated and the registry is network-segmented.

An attacker reaches the registry's artifact-upload API (no credentials needed against a default-config deployment) and POSTs a small XML artifact whose DOCTYPE references an external parameter entity at an attacker- or internal-pointing URL. The server's SAX parser fetches that URL, letting the attacker blind-SSRF into the internal network (e.g., probe cloud metadata or internal admin services) or, by supplying recursively nested entities, exhaust server CPU/memory to cause denial of service. No public exploit is identified at time of analysis, but the low attack complexity (AC:L) and absence of required user interaction make weaponization straightforward.