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CVE-2026-123635 Refused calls drain the HTTP/2 connection flow-control window in elixir-grpc grpc_server

6.3 mediumFix available

Medium (6.3) in elixir-grpc grpc server. Fixed in grpc_server 1.1.0.

On this page
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.

Severity

CVSS 4.0

6.3 medium
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
CWE
CWE-772 Missing Release of Resource after Effective Lifetime
Published
Assigned by
EEF (CNA)
NVD analysis
Awaiting analysis
Record from
the NVD, synced

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Affected

Versions

From the CNA's record in the CVE List.

ProductAffected
elixir-grpc grpc_serverfrom 1.0.0 before 1.1.0

Fix and patched versions

  • grpc_server (Hex): fixed in 1.1.0

Packages (OSV)

AdvisoryEcosystemPackageAffectedFixed in
EEF-CVE-2026-123635Hexgrpc_server>=1.0.0 <1.1.01.1.0
EEF-CVE-2026-123635v1.0.6, v1.0.3, v1.0.0no fix published

Attack patterns (CAPEC)

The attack patterns MITRE's CAPEC relates to this record's weaknesses, as MITRE names them. Credits.

References

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