CVE-2026-123635
Refused calls drain the HTTP/2 connection flow-control window in elixir-grpc grpc_server
Description
Missing Release of Resource after Effective Lifetime vulnerability in elixir-grpc grpc_server allows a client to stall all later calls on a shared HTTP/2 connection via calls that the server refuses while their DATA frames are in flight. The stream handler grpc_stream_h (grpc_server/src/grpc_stream_h.erl) requests flow from Cowboy only for request data that has arrived. When the server refuses a call early, for example because the body exceeds max_body_size or the method is not implemented, Cowboy drops the DATA frames still in flight for that stream. Their bytes are not returned to the connection flow-control window. After enough refused calls the window is empty. No call on that connection can then send a request body, and each call waits until its deadline. Other connections are not affected. This issue affects grpc_server: from 1.0.0 before 1.1.0.
INFO
Published Date :
Nov. 13, 2026, 4:17 p.m.
Last Modified :
Nov. 13, 2026, 4:17 p.m.
Remotely Exploit :
Yes !
Source :
6b3ad84c-e1a6-4bf7-a703-f496b71e49db
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 4.0 | MEDIUM | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | ||||
| CVSS 4.0 | MEDIUM | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db |
Solution
- Update elixir-grpc to version 1.1.0 or later.
- Apply vendor-provided patches for earlier versions.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-123635.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-123635 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-123635
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-123635 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-123635 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
Nov. 13, 2026
Action Type Old Value New Value Added Description Missing Release of Resource after Effective Lifetime vulnerability in elixir-grpc grpc_server allows a client to stall all later calls on a shared HTTP/2 connection via calls that the server refuses while their DATA frames are in flight. The stream handler grpc_stream_h (grpc_server/src/grpc_stream_h.erl) requests flow from Cowboy only for request data that has arrived. When the server refuses a call early, for example because the body exceeds max_body_size or the method is not implemented, Cowboy drops the DATA frames still in flight for that stream. Their bytes are not returned to the connection flow-control window. After enough refused calls the window is empty. No call on that connection can then send a request body, and each call waits until its deadline. Other connections are not affected. This issue affects grpc_server: from 1.0.0 before 1.1.0. Added CVSS V4.0 AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/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 Added CWE CWE-772 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/123xxx/CVE-2026-123635.json">CVE-2026-123635</a> Added Reference https://cna.erlef.org/cves/CVE-2026-123635.html Added Reference https://github.com/elixir-grpc/grpc/commit/0332faae5f5e132314794dbfdae5edecbccea292 Added Reference https://github.com/elixir-grpc/grpc/commit/61a71948e6e7b95efb27d48e7084c764503cc802 Added Reference https://github.com/elixir-grpc/grpc/security/advisories/GHSA-7x9q-vvph-rjcr Added Reference https://osv.dev/vulnerability/EEF-CVE-2026-123635