CVE-2023-33953
Google LLC · published 2023-08-09
Source record Collected from the National Vulnerability Database (NVD)
Description
Description by Google Inc. via the CVE Program.
gRPC contains a vulnerability that allows hpack table accounting errors could lead to unwanted disconnects between clients and servers in exceptional cases/ Three vectors were found that allow the following DOS attacks: - Unbounded memory buffering in the HPACK parser - Unbounded CPU consumption in the HPACK parser The unbounded CPU consumption is down to a copy that occurred per-input-block in the parser, and because that could be unbounded due to the memory copy bug we end up with an O(n^2) parsing loop, with n selected by the client. The unbounded memory buffering bugs: - The header size limit check was behind the string reading code, so we needed to first buffer up to a 4 gigabyte string before rejecting it as longer than 8 or 16kb. - HPACK varints have an encoding quirk whereby an infinite number of 0’s can be added at the start of an integer. gRPC’s hpack parser needed to read all of them before concluding a parse. - gRPC’s metadata overflow check was performed per frame, so that the following sequence of frames could cause infinite buffering: HEADERS: containing a: 1 CONTINUATION: containing a: 2 CONTINUATION: containing a: 3 etc…
Status at the source
- NVD status: Modified
Affected products, as the source lists them
| Vendor | Product | Versions |
|---|---|---|
| gRPC | 0 – before 1.56.1: affected |
Added by CISA-ADP (Authorized Data Publisher)
| Vendor | Product | Versions |
|---|---|---|
| grpc | grpc | 0 – before 1.53.2: affected 1.54 – before 154.3: affected 1.55 – before 1.55.2: affected 1.56 – before 1.56.2: affected |
Products named in NVD's CPE match criteria (1)
cpe:2.3:a:grpc:grpc:*:*:*:*:*:-:*:*
DeSpy has not checked any unit, hardware revision or firmware. A product missing here is not a statement that it is unaffected.
Scores, as their sources published them
- CVSS 3.1: 7.5 HIGH — as published by Google Inc. (Secondary)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - CVSS 3.1: 7.5 HIGH — as published by NIST (Primary)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - SSVC — CISA's assessment (SSVC 2.0.3, CISA Coordinator): Exploitation: none · Automatable: yes · Technical impact: partial
DeSpy does not score records. These are the sources' own values.
Weaknesses
Sources
References the source lists
- https://cloud.google.com/support/bulletins#gcp-2023-022
- https://cloud.google.com/support/bulletins#gcp-2023-022
Source dates: published 2023-08-09, last changed 2026-06-17. DeSpy's copy of this version is dated 2026-09-28.
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