PT-2026-56540 · Smallnest · Rpcx

George Chen · Published 2026-07-08 · Updated 2026-07-08 · CVE-2026-59803

Mitre

CVSS v3.1

7.5

High

Base vector

AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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.

Exploit

Fix

Weakness Enumeration

CWE-409

Related Identifiers

CVE-2026-59803

Affected Products

Rpcx

References · 5

• 🔥 https://github.com/smallnest/rpcx/issues/942 · Exploit
• https://github.com/smallnest/rpcx/commit/047aec18efa7d037105e2b72c36dd2ae05e1acc6 · Patch
• https://nvd.nist.gov/vuln/detail/CVE-2026-59803 · Security Note
• https://github.com/smallnest/rpcx/pull/943 · Note
• https://vulncheck.com/advisories/rpcx-denial-of-service-via-gzip-decompression-bomb-in-wire-protocol · Note