CVE-2026-59803 PUBLISHED

rpcx - Denial of Service via Gzip Decompression Bomb in Wire Protocol

Assigner: VulnCheck
Reserved: 07.07.2026 Published: 08.07.2026 Updated: 09.07.2026

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.

Metrics

CVSS 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
CVSS Score: 8.7

Product Status

Vendor smallnest
Product rpcx
Versions Default: unaffected
  • affected from 0 to 1.9.3 (incl.)
  • Version 047aec18efa7d037105e2b72c36dd2ae05e1acc6 is unaffected

Credits

  • George Chen finder

References

Problem Types

  • Improper Handling of Highly Compressed Data (Data Amplification) CWE