# Netty: HTTP/2 decompression leaks ByteBuf reference count when the decompressor channel is already closed (Direct memory leak / OOM DoS) Advisory record · `GHSA-93wv-jw9v-4972` - **Identifiers:** `GHSA-93wv-jw9v-4972` · `CVE-2026-56819` - **State:** Confirmed - **Severity:** CVSS 7.5 High - **Critical:** No - **Weakness (CWE):** [CWE-400](https://cwe.mitre.org/data/definitions/400.html) · [CWE-401](https://cwe.mitre.org/data/definitions/401.html) - **Tags:** [Denial of service](https://agentprime.io/advisories/tag/dos.md) - **Published:** 31 Jul 2026 - **Updated:** 10 Sept 2026 - **Reviewed by a person:** No Published by the GitHub Advisory Database at 31 Jul 2026, 16:51 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. ## Affected packages - `io.netty:netty-codec-http2` (Maven): affected `>=4.2.0, <4.2.16.Final || >=4.1.0.Final, <4.1.136.Final`; fixed in `4.2.16.Final`, `4.1.136.Final` ## Machine-written summary Summary written by Claude Haiku from the source advisory. Not reviewed by a person. > Netty's codec-http2 package is vulnerable in versions from 4.2.0 up to but not including 4.2.16.Final and from 4.1.0.Final up to but not including 4.1.136.Final. A remote, unauthenticated peer can send HTTP/2 DATA frames for a stream whose decompressor has already been closed, which leaks one direct ByteBuf per frame when HTTP/2 content decompression is enabled. Repeated over a long-lived connection, this can exhaust direct memory and crash the JVM with an OutOfMemoryError. Upgrade to 4.2.16.Final or 4.1.136.Final. Written 2 Nov 2026. ## Not analysed yet We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check. ## Severity and exploitation - 7.5 High, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`, from CNA (GitHub_M) - **CISA KEV:** Not listed. - **EPSS:** 0.0066, the 52nd percentile, on 8 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days. ## Timeline - 31 Oct 2026, 14:16 UTC: First seen by agentprime - 31 Oct 2026, 14:16 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-93wv-jw9v-4972) ## Sources - [GitHub Advisory Database: GHSA-93wv-jw9v-4972](https://github.com/advisories/GHSA-93wv-jw9v-4972) - [OSV: GHSA-93wv-jw9v-4972](https://osv.dev/vulnerability/GHSA-93wv-jw9v-4972) - - - - - - - Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code. ## Check whether this affects you A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet. - With the agentprime MCP server (), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: - In a browser: reads your lockfile in the browser, never uploading it. - Whether it touches your code, with file and line: the Claude Code plugin, - As JSON: , or `POST https://api.agentprime.io/v1/match` with your packages () --- The web page: . Everything for agents: .