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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.

PUBLISHED Reserved 2026-07-07 | Published 2026-07-08 | Updated 2026-07-09 | Assigner VulnCheck




HIGH: 8.7CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

HIGH: 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Problem types

Improper Handling of Highly Compressed Data (Data Amplification)

Product status

Default status
unaffected

Any version
affected

047aec18efa7d037105e2b72c36dd2ae05e1acc6 (git)
unaffected

Credits

George Chen finder

References

github.com/smallnest/rpcx/issues/942 (Researcher Disclosure) technical-description exploit

github.com/smallnest/rpcx/pull/943 (Fix PR) issue-tracking

github.com/...ommit/047aec18efa7d037105e2b72c36dd2ae05e1acc6 (Fix Commit) patch

www.vulncheck.com/...zip-decompression-bomb-in-wire-protocol third-party-advisory

cve.org (CVE-2026-59803)

nvd.nist.gov (CVE-2026-59803)

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