Vulnerability Details CVE-2023-33953
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…
Exploit prediction scoring system (EPSS) score
EPSS Score 0.001
EPSS Ranking 28.9%
CVSS Severity
CVSS v3 Score 7.5
References
Products affected by CVE-2023-33953
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cpe:2.3:a:grpc:grpc:0.12.0
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cpe:2.3:a:grpc:grpc:0.13.0
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cpe:2.3:a:grpc:grpc:0.13.1
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cpe:2.3:a:grpc:grpc:0.14.0
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cpe:2.3:a:grpc:grpc:0.14.1
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cpe:2.3:a:grpc:grpc:0.15.0
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cpe:2.3:a:grpc:grpc:0.5.0
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cpe:2.3:a:grpc:grpc:0.6.0
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cpe:2.3:a:grpc:grpc:0.9.0
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cpe:2.3:a:grpc:grpc:0.9.1
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cpe:2.3:a:grpc:grpc:1.0.0
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cpe:2.3:a:grpc:grpc:1.0.1
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cpe:2.3:a:grpc:grpc:1.1.0
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cpe:2.3:a:grpc:grpc:1.1.1
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cpe:2.3:a:grpc:grpc:1.1.2
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cpe:2.3:a:grpc:grpc:1.1.3
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cpe:2.3:a:grpc:grpc:1.1.4
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cpe:2.3:a:grpc:grpc:1.10.0
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cpe:2.3:a:grpc:grpc:1.10.1
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cpe:2.3:a:grpc:grpc:1.11.0
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cpe:2.3:a:grpc:grpc:1.12.0
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cpe:2.3:a:grpc:grpc:1.12.1
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cpe:2.3:a:grpc:grpc:1.13.0
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cpe:2.3:a:grpc:grpc:1.13.1
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cpe:2.3:a:grpc:grpc:1.14.0
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cpe:2.3:a:grpc:grpc:1.14.1
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cpe:2.3:a:grpc:grpc:1.14.2
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cpe:2.3:a:grpc:grpc:1.15.0
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cpe:2.3:a:grpc:grpc:1.15.1
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cpe:2.3:a:grpc:grpc:1.16.0
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cpe:2.3:a:grpc:grpc:1.16.1
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cpe:2.3:a:grpc:grpc:1.17.0
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cpe:2.3:a:grpc:grpc:1.17.1
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cpe:2.3:a:grpc:grpc:1.17.2
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cpe:2.3:a:grpc:grpc:1.18.0
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cpe:2.3:a:grpc:grpc:1.19.0
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cpe:2.3:a:grpc:grpc:1.2.0
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cpe:2.3:a:grpc:grpc:1.2.1
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cpe:2.3:a:grpc:grpc:1.20.0
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cpe:2.3:a:grpc:grpc:1.20.2
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cpe:2.3:a:grpc:grpc:1.20.3
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cpe:2.3:a:grpc:grpc:1.21.0
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cpe:2.3:a:grpc:grpc:1.22.0
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cpe:2.3:a:grpc:grpc:1.22.2
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cpe:2.3:a:grpc:grpc:1.23.3
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cpe:2.3:a:grpc:grpc:1.23.4
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cpe:2.3:a:grpc:grpc:1.24.2
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cpe:2.3:a:grpc:grpc:1.24.3
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cpe:2.3:a:grpc:grpc:1.24.4
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cpe:2.3:a:grpc:grpc:1.25.0
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cpe:2.3:a:grpc:grpc:1.26.0
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cpe:2.3:a:grpc:grpc:1.27.0
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cpe:2.3:a:grpc:grpc:1.27.1
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cpe:2.3:a:grpc:grpc:1.27.2
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cpe:2.3:a:grpc:grpc:1.27.3
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cpe:2.3:a:grpc:grpc:1.28.0
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cpe:2.3:a:grpc:grpc:1.28.1
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cpe:2.3:a:grpc:grpc:1.28.2
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cpe:2.3:a:grpc:grpc:1.29.0
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cpe:2.3:a:grpc:grpc:1.29.1
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cpe:2.3:a:grpc:grpc:1.3.0
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cpe:2.3:a:grpc:grpc:1.3.1
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cpe:2.3:a:grpc:grpc:1.30.0
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cpe:2.3:a:grpc:grpc:1.30.1
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cpe:2.3:a:grpc:grpc:1.30.2
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cpe:2.3:a:grpc:grpc:1.31.0
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cpe:2.3:a:grpc:grpc:1.31.1
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cpe:2.3:a:grpc:grpc:1.32.0
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cpe:2.3:a:grpc:grpc:1.33.0
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cpe:2.3:a:grpc:grpc:1.33.1
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cpe:2.3:a:grpc:grpc:1.33.2
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cpe:2.3:a:grpc:grpc:1.34.0
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cpe:2.3:a:grpc:grpc:1.34.1
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cpe:2.3:a:grpc:grpc:1.35.0
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cpe:2.3:a:grpc:grpc:1.36.0
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cpe:2.3:a:grpc:grpc:1.36.1
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cpe:2.3:a:grpc:grpc:1.36.2
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cpe:2.3:a:grpc:grpc:1.36.3
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cpe:2.3:a:grpc:grpc:1.36.4
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cpe:2.3:a:grpc:grpc:1.37.0
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cpe:2.3:a:grpc:grpc:1.37.1
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cpe:2.3:a:grpc:grpc:1.38.0
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cpe:2.3:a:grpc:grpc:1.38.1
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cpe:2.3:a:grpc:grpc:1.39.0
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cpe:2.3:a:grpc:grpc:1.39.1
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cpe:2.3:a:grpc:grpc:1.4.0
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cpe:2.3:a:grpc:grpc:1.40.0
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cpe:2.3:a:grpc:grpc:1.41.0
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cpe:2.3:a:grpc:grpc:1.41.1
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cpe:2.3:a:grpc:grpc:1.42.0
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cpe:2.3:a:grpc:grpc:1.43.0
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cpe:2.3:a:grpc:grpc:1.43.2
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cpe:2.3:a:grpc:grpc:1.44.0
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cpe:2.3:a:grpc:grpc:1.44.1
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cpe:2.3:a:grpc:grpc:1.45.0
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cpe:2.3:a:grpc:grpc:1.45.1
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cpe:2.3:a:grpc:grpc:1.45.2
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cpe:2.3:a:grpc:grpc:1.45.3
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cpe:2.3:a:grpc:grpc:1.46.0
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cpe:2.3:a:grpc:grpc:1.46.1
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cpe:2.3:a:grpc:grpc:1.46.2
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cpe:2.3:a:grpc:grpc:1.46.3
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cpe:2.3:a:grpc:grpc:1.46.4
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cpe:2.3:a:grpc:grpc:1.46.5
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cpe:2.3:a:grpc:grpc:1.46.6
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cpe:2.3:a:grpc:grpc:1.46.7
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cpe:2.3:a:grpc:grpc:1.47.0
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cpe:2.3:a:grpc:grpc:1.47.1
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cpe:2.3:a:grpc:grpc:1.47.2
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cpe:2.3:a:grpc:grpc:1.47.3
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cpe:2.3:a:grpc:grpc:1.47.4
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cpe:2.3:a:grpc:grpc:1.47.5
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cpe:2.3:a:grpc:grpc:1.48.0
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cpe:2.3:a:grpc:grpc:1.48.1
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cpe:2.3:a:grpc:grpc:1.48.2
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cpe:2.3:a:grpc:grpc:1.48.3
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cpe:2.3:a:grpc:grpc:1.48.4
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cpe:2.3:a:grpc:grpc:1.49.0
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cpe:2.3:a:grpc:grpc:1.49.1
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cpe:2.3:a:grpc:grpc:1.49.2
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cpe:2.3:a:grpc:grpc:1.49.3
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cpe:2.3:a:grpc:grpc:1.50.0
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cpe:2.3:a:grpc:grpc:1.50.1
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cpe:2.3:a:grpc:grpc:1.50.2
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cpe:2.3:a:grpc:grpc:1.51.0
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cpe:2.3:a:grpc:grpc:1.51.1
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cpe:2.3:a:grpc:grpc:1.51.2
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cpe:2.3:a:grpc:grpc:1.51.3
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cpe:2.3:a:grpc:grpc:1.52.0
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cpe:2.3:a:grpc:grpc:1.52.1
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cpe:2.3:a:grpc:grpc:1.52.2
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cpe:2.3:a:grpc:grpc:1.53.0
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cpe:2.3:a:grpc:grpc:1.53.1
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cpe:2.3:a:grpc:grpc:1.54.0
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cpe:2.3:a:grpc:grpc:1.54.1
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cpe:2.3:a:grpc:grpc:1.54.2
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cpe:2.3:a:grpc:grpc:1.55.0
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cpe:2.3:a:grpc:grpc:1.55.1
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cpe:2.3:a:grpc:grpc:1.56.0
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cpe:2.3:a:grpc:grpc:1.56.1
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cpe:2.3:a:grpc:grpc:1.6.1
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cpe:2.3:a:grpc:grpc:1.7.0
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cpe:2.3:a:grpc:grpc:1.7.1
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cpe:2.3:a:grpc:grpc:1.8.0
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cpe:2.3:a:grpc:grpc:1.9.0
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cpe:2.3:a:grpc:grpc:1.9.1