grpc_server: Interpretation Conflict
CVE-2026-124278 is a high-severity interpretation conflict vulnerability in grpc_server from Elixir-grpc, with a CVSS 4.0 base score of 7.6 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. The record lists versions 1.1.0, 953ab980d8a127e895d3ab9505fc4b9337bb32f7 as the first without the flaw, so updating grpc_server to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.5% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update grpc_server to 1.1.0 or 953ab980d8a127e895d3ab9505fc4b9337bb32f7, whichever matches your release line, or a later version.
- Update grpc to 1.0.0 or 0332faae5f5e132314794dbfdae5edecbccea292, whichever matches your release line, or a later version.
- Read the advisory on github.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Elixir-grpc | grpc_server | 1.0.0 up to, but not including, 1.1.0; 0332faae5f5e132314794dbfdae5edecbccea292 up to, but not including, 953ab980d8a127e895d3ab9505fc4b9337bb32f7 | 1.1.0, 953ab980d8a127e895d3ab9505fc4b9337bb32f7 |
| Elixir-grpc | grpc | 0.8.0 up to, but not including, 1.0.0; 8aaf3d3a8c4c7b08ac65e9c6f254e0d24da1d048 up to, but not including, 0332faae5f5e132314794dbfdae5edecbccea292 | 1.0.0, 0332faae5f5e132314794dbfdae5edecbccea292 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Attack requirements
- PresentThe target must be in a specific state or configuration for the attack to work.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Confidentiality (vulnerable system)
- HighSerious loss of confidentiality on the vulnerable system.
- Integrity (vulnerable system)
- HighSerious loss of integrity on the vulnerable system.
- Availability (vulnerable system)
- NoneNo loss of availability on the vulnerable system.
- Confidentiality (other systems)
- NoneNo loss of confidentiality on systems beyond the vulnerable one.
- Integrity (other systems)
- NoneNo loss of integrity on systems beyond the vulnerable one.
- Availability (other systems)
- NoneNo loss of availability on systems beyond the vulnerable one.
Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. Scored by CNA.
Official description
Authorization Bypass Through User-Controlled Key vulnerability in elixir-grpc grpc_server and grpc allows an attacker to make a handler act on a resource other than the one named in the URL of an HTTP-transcoded route, via a request with a gRPC Content-Type. Only the transcoding clause of GRPC.Server.do_handle_request/4 (grpc_server/lib/grpc/server.ex, and lib/grpc/server.ex before the package split) applies the route's path bindings to the request message. The Cowboy handler picks that clause from the request Content-Type, not from the route. A request to a transcoded URL with application/grpc or application/grpc-web is decoded from the body alone, so every path-bound field takes its value from the body. A gateway, proxy rule or WAF that authorizes on the URL path sees one resource while the handler receives another. This issue affects grpc_server: from 1.0.0 before 1.1.0; grpc: from 0.8.0 before 1.0.0.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Interpretation Conflict
Product A handles inputs or steps differently than Product B, which causes A to perform incorrect actions based on its perception of B's state.
Timeline
- CVE record published.
References
Patches and release notes
Other vulnerabilities in grpc_server
- 8.2 High severity
- 8.2 High severity
- 8.2 High severity
Recent Interpretation Conflict vulnerabilities
- 7.0 High severity
- 8.6 High severity
- 7.5 High severity
- 9.9 Critical severity
- 8.8 High severity
- 9.1 Critical severity
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