GHSA-cfgp-2977-2fmm: io.grpc:grpc-protobuf (CVE-2023-32731)

Package	Ecosystem	Affected	Fixed in
io.grpc:grpc-protobuf	Maven	>=1.53.0, <1.53.1 \|\| >=1.54.0, <1.54.2	1.53.1, 1.54.2
grpcio	PyPI	>=1.53.0, <1.53.1 \|\| >=1.54.0, <1.54.2	1.53.1, 1.54.2
grpc	RubyGems	>=1.53.0, <1.53.1 \|\| >=1.54.0, <1.54.2	1.53.1, 1.54.2

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Three packages are affected: io.grpc:grpc-protobuf (Maven), grpcio (PyPI), and grpc (RubyGems), in versions 1.53.0 to before 1.53.1 and 1.54.0 to before 1.54.2. When a header-size error occurred, gRPC's HTTP/2 stack skipped parsing the rest of an HPACK frame, causing HPACK table desynchronization between sender and receiver. The source gives few details on the exact attacker position, but it describes requests from a proxy being interpreted with headers from other clients, leading to information leaks. Upgrade to version 1.53.1 or 1.54.2 of the affected package.

Written 2 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
7.4	High	3.1	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H	CNA (Google)

CISA KEV Not listed.
EPSS 0.0050, the 42nd percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

31 Oct 2026, 14:18 UTC First seen by agentprime
31 Oct 2026, 14:18 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.