CVE-2026-33186 | grpc grpc-go up to 1.79.2 improper authorization

VDB-352149 · CVE-2026-33186 · GCVE-0-2026-33186 GRPC GRPC-GO UP TO 1.79.2 IMPROPER AUTHORIZATION HISTORYDIFFRELATEJSONXMLCTI CVSS Meta Temp Score Current Exploit Price (≈) CTI Interest Score 8.0 $0-$5k 1.77+ Summaryinfo A vulnerability was found in grpc grpc-go up to 1.79.2. It has been rated as critical. The affected element is an unknown function. Performing a manipulation results in improper authorization. This vulnerability is cataloged as CVE-2026-33186. It is possible to initiate the attack remotely. There is no exploit available. Upgrading the affected component is advised. Detailsinfo A vulnerability was found in grpc grpc-go up to 1.79.2. It has been classified as critical. This affects an unknown function. The manipulation with an unknown input leads to a improper authorization vulnerability. CWE is classifying the issue as CWE-285. The product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is: gRPC-Go is the Go language implementation of gRPC. Versions prior to 1.79.3 have an authorization bypass resulting from improper input validation of the HTTP/2 `:path` pseudo-header. The gRPC-Go server was too lenient in its routing logic, accepting requests where the `:path` omitted the mandatory leading slash (e.g., `Service/Method` instead of `/Service/Method`). While the server successfully routed these requests to the correct handler, authorization interceptors (including the official `grpc/authz` package) evaluated the raw, non-canonical path string. Consequently, "deny" rules defined using canonical paths (starting with `/`) failed to match the incoming request, allowing it to bypass the policy if a fallback "allow" rule was present. This affects gRPC-Go servers that use path-based authorization interceptors, such as the official RBAC implementation in `google.golang.org/grpc/authz` or custom interceptors relying on `info.FullMethod` or `grpc.Method(ctx)`; AND that have a security policy contains specific "deny" rules for canonical paths but allows other requests by default (a fallback "allow" rule). The vulnerability is exploitable by an attacker who can send raw HTTP/2 frames with malformed `:path` headers directly to the gRPC server. The fix in version 1.79.3 ensures that any request with a `:path` that does not start with a leading slash is immediately rejected with a `codes.Unimplemented` error, preventing it from reaching authorization interceptors or handlers with a non-canonical path string. While upgrading is the most secure and recommended path, users can mitigate the vulnerability using one of the following methods: Use a validating interceptor (recommended mitigation); infrastructure-level normalization; and/or policy hardening. The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2026-33186 since 03/17/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Neither technical details nor an exploit are publicly available. MITRE ATT&CK project uses the attack technique T1548.002 for this issue. Upgrading to version 1.79.3 eliminates this vulnerability. Productinfo Vendor grpc Name grpc-go Version 1.79.0 1.79.1 1.79.2 Website Product: https://github.com/grpc/grpc-go/ CPE 2.3info 🔒 🔒 🔒 CPE 2.2info 🔒 🔒 🔒 CVSSv4info VulDB Vector: 🔒 VulDB Reliability: 🔍 CVSSv3info VulDB Meta Base Score: 8.2 VulDB Meta Temp Score: 8.0 VulDB Base Score: 7.3 VulDB Temp Score: 7.0 VulDB Vector: 🔒 VulDB Reliability: 🔍 CNA Base Score: 9.1 CNA Vector (GitHub_M): 🔒 CVSSv2info Vector Complexity Authentication Confidentiality Integrity Availability Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock VulDB Base Score: 🔒 VulDB Temp Score: 🔒 VulDB Reliability: 🔍 Exploitinginfo Class: Improper authorization CWE: CWE-285 / CWE-266 CAPEC: 🔒 ATT&CK: 🔒 Physical: No Local: No Remote: Yes Availability: 🔒 Status: Not defined Price Prediction: 🔍 Current Price Estimation: 🔒 0-Day Unlock Unlock Unlock Unlock Today Unlock Unlock Unlock Unlock Threat Intelligenceinfo Interest: 🔍 Active Actors: 🔍 Active APT Groups: 🔍 Countermeasuresinfo Recommended: Upgrade Status: 🔍 0-Day Time: 🔒 Upgrade: grpc-go 1.79.3 Timelineinfo 03/17/2026 CVE reserved 03/20/2026 +3 days Advisory disclosed 03/20/2026 +0 days VulDB entry created 03/20/2026 +0 days VulDB entry last update Sourcesinfo Product: github.com Advisory: github.com Status: Confirmed CVE: CVE-2026-33186 (🔒) GCVE (CVE): GCVE-0-2026-33186 GCVE (VulDB): GCVE-100-352149 Entryinfo Created: 03/20/2026 23:36 Changes: 03/20/2026 23:36 (63) Complete: 🔍 Cache ID: 99:F4B:101 Discussion No comments yet. Languages: en. Please log in to comment. ◂ PreviousOverviewNext ▸