CVE-2026-59902 is a high-severity (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in io.netty:netty-transport-sctp. A fix is available for io.netty:netty-transport-sctp — see the affected versions and patch details below.
Netty: Memory Exhaustion in SctpMessageCompletionHandler
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-59902.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-59902 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 381,682 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
io.netty:netty-transport-sctp☕io.netty:netty-transport-sctpReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
Summary
SctpMessageCompletionHandler does not limit the total size of buffered fragments, allowing an unauthenticated attacker to cause an OutOfMemoryError by sending large SCTP fragments.
Details
io.netty.handler.codec.sctp.SctpMessageCompletionHandler buffers fragments for incomplete SCTP messages. The fix for CVE-2026-46340 fixed unbounded memory growth by introducing limits on the number of concurrent incomplete messages (maxIncompleteSctpMessages) and the number of fragments per message (maxFragments).
While the count of fragments is now bounded, the handler still does not enforce a maximum size in bytes.
With the default limits of 128 messages and 128 fragments, and a typical max SCTP chunk size of 64KB, an attacker can consume up to ~1GB per connection. By opening a small number of concurrent connections, an attacker can easily exhaust the server's memory, causing an OutOfMemoryError.
Impact
Memory Exhaustion. Any application using Netty's SCTP transport with SctpMessageCompletionHandler is impacted.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | io.netty:netty-transport-sctp | ≥ 4.2.0.Final&&< 4.2.17.Final | 4.2.17.Finalio.netty:netty-transport-sctp:4.2.17.Final |
| ☕Maven | io.netty:netty-transport-sctp | all versions | 4.1.137.Finalio.netty:netty-transport-sctp:4.1.137.Final |
Affected Products
nettynettyDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.netty:netty-transport-sctp, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update io.netty:netty-transport-sctp to 4.2.17.Final or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-59902 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat build of Apache Camel 4.18.4 for Spring Boot 3.5.16 | netty-transport-sctp | RHSA-2026:71675 |
Frequently Asked Questions
Is CVE-2026-59902 in your dependencies?
Find it across Maven, including transitive dependencies.