Netty: SCTP reassembly nests buffers without bound

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-46340: 0.61% estimated exploitation activity in the next 30 days; percentile 49.06 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

For each non-complete SctpMessage fragment the handler does fragments.put(streamId, Unpooled.wrappedBuffer(frag, byteBuf)), wrapping the previous accumulator and the new slice into a new CompositeByteBuf every time. After N fragments the accumulator is an N-deep chain of composites, each holding references and component arrays; readableBytes()/getBytes() on the final buffer recurse N levels. There is no limit on N, on total bytes, or on the number of streamIdentifiers an attacker can open (each gets its own map entry). A peer that never sets the complete flag can grow this structure indefinitely from tiny 1-byte DATA chunks.

Published by the source

8 Jun 2026, 23:02 UTC

Last modified by the source

12 Jun 2026, 19:29 UTC

Source last checked

26 Oct 2026, 16:46 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-5xrh-qmmq-w6ch

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# Patch Next advisory brief: CVE-2026-46340

Advisory: Netty: SCTP reassembly nests buffers without bound
IDs: CVE-2026-46340, GHSA-5xrh-qmmq-w6ch
Record: https://patchnext.com/advisories/cve-2026-46340 (revision 1, source checked 26 Oct 2026, 16:46 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: io.netty:netty-transport-sctp 4.2.15.Final, 4.1.135.Final. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven io.netty:netty-transport-sctp: affected >= 4.2.0.Final, <= 4.2.14.Final; <= 4.1.134.Final; fixed in 4.2.15.Final, 4.1.135.Final

## Suggested inspection (read-only)
- Maven io.netty:netty-transport-sctp: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on io.netty:netty-transport-sctp.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-5xrh-qmmq-w6ch (GitHub-reviewed advisory GHSA-5xrh-qmmq-w6ch lists affected ranges: Maven io.netty:netty-transport-sctp >=4.2.0.Final =0 <=4.1.134.Final)

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