# CVE-2026-59803

## Summary

- **CVE ID:** CVE-2026-59803
- **Severity:** HIGH
- **CVSS Score:** 8.7 (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)
- **CWE:** CWE-409
- **Published:** Jul 8, 2026
- **Last Modified:** Jul 9, 2026

## Description

rpcx through 1.9.3, fixed in commit 047aec1, contains a denial-of-service vulnerability in protocol.Message.Decode (protocol/message.go). When a message has the compression flag set, the payload is gzip-decompressed via util.Unzip with no limit on the decompressed output size. The only built-in size guard, protocol.MaxMessageLength, is checked against the compressed on-the-wire frame length, not the decompressed size, so it provides no protection. Because decoding (and decompression) occurs in readRequest before authentication, a single unauthenticated connection can send a small (under 2 MB) gzip-compressed message that expands to gigabytes of heap allocation, leading to out-of-memory conditions and service unavailability.

## Affected Products

- smallnest — rpcx (0)
- smallnest — rpcx (047aec18efa7d037105e2b72c36dd2ae05e1acc6)

## References

- [CNA](https://github.com/smallnest/rpcx/issues/942)
- [CNA](https://github.com/smallnest/rpcx/pull/943)
- [CNA](https://github.com/smallnest/rpcx/commit/047aec18efa7d037105e2b72c36dd2ae05e1acc6)
- [CNA](https://www.vulncheck.com/advisories/rpcx-denial-of-service-via-gzip-decompression-bomb-in-wire-protocol)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.74%
- **EPSS Percentile:** 52.5

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._