Allocation of Resources Without Limits or Throttling Affecting grpc package, versions *


Severity

Recommended
0.0
high
0
10

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Threat Intelligence

EPSS
0.08% (38th percentile)

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  • Snyk IDSNYK-DEBIANUNSTABLE-GRPC-5840618
  • published13 Aug 2023
  • disclosed9 Aug 2023

Introduced: 9 Aug 2023

CVE-2023-33953  (opens in a new tab)
CWE-770  (opens in a new tab)
CWE-834  (opens in a new tab)

How to fix?

There is no fixed version for Debian:unstable grpc.

NVD Description

Note: Versions mentioned in the description apply only to the upstream grpc package and not the grpc package as distributed by Debian. See How to fix? for Debian:unstable relevant fixed versions and status.

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…

CVSS Scores

version 3.1