elixir-grpc 0.x gzip.ex data amplification

Summaryinfo

A vulnerability identified as problematic has been detected in elixir-grpc grpc 0.x. The affected element is an unknown function in the library lib/grpc/compressor/gzip.ex. This manipulation causes data amplification. This vulnerability is handled as CVE-2026-53430. The attack can be initiated remotely. There is not any exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic was found in elixir-grpc grpc 0.x. Affected by this vulnerability is some unknown functionality in the library lib/grpc/compressor/gzip.ex. The manipulation with an unknown input leads to a data amplification vulnerability. The CWE definition for the vulnerability is CWE-409. The product does not handle or incorrectly handles a compressed input with a very high compression ratio that produces a large output. As an impact it is known to affect availability. The summary by CVE is:

Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in elixir-grpc grpc (GRPC.Compressor.Gzip, GRPC.Message modules) allows a denial of service via a gzip decompression bomb. This vulnerability is associated with program files lib/grpc/compressor/gzip.ex, lib/grpc/message.ex and program routines 'Elixir.GRPC.Compressor.Gzip':decompress/1, 'Elixir.GRPC.Message':from_data/2. 'Elixir.GRPC.Compressor.Gzip':decompress/1 calls :zlib.gunzip/1 directly on attacker-controlled bytes with no decompressed-size limit, ratio check, or incremental decoding. Because this module is the registered gzip GRPC.Compressor implementation, it is invoked automatically whenever an incoming gRPC frame carries the grpc-encoding: gzip header. :zlib.gunzip/1 allocates the entire decompressed result as a single binary, so a small highly compressible payload (for example a few kilobytes of zeros, which gzip compresses at roughly 1000:1) expands to multiple gigabytes inside a single call. The max_receive_message_length limit is enforced only against the already-decompressed message, so it provides no protection. An unauthenticated remote peer can send a single crafted frame to exhaust the BEAM node's heap and trigger an out-of-memory kill. This issue affects grpc: from 0.4.0 before 1.0.0.

The weakness was released by Peter Ullrich as GHSA-6ccx-9c9f-327w. The advisory is shared at github.com. This vulnerability is known as CVE-2026-53430 since 06/09/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1499 for this issue.

Upgrading to version 1.0.0 eliminates this vulnerability. Applying the patch 1afbab9d57d2a3e16ca9c62ffa4923338ea96cfc is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Vendor

• elixir-grpc

Name

• grpc

Version

• 0.x

License

• open-source

Website

• Product: https://github.com/elixir-grpc/grpc/

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