CVE-2026-59803 rpcx - Denial of Service via Gzip Decompression Bomb in Wire Protocol
An unauthenticated attacker can cause a denial of service in rpcx by sending a small gzip-compressed message that expands to consume excessive memory.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-59803?
CVE-2026-59803 is a high-severity denial of service vulnerability in smallnest rpcx, published on 8 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-409
Which versions are affected by CVE-2026-59803?
How do I fix CVE-2026-59803?
No fix has been published for CVE-2026-59803 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-59803 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-59803 exists.
Sources
Also known as GHSA-hgrm-22x6-r8c8.