# Undertow Servlets Vulnerable to Remote DoS via OutOfMemoryError when Passed Large Parameter Names Advisory record · `GHSA-33hj-rcmx-86mv` - **Identifiers:** `GHSA-33hj-rcmx-86mv` · `CVE-2024-4027` - **State:** Confirmed - **Severity:** CVSS 7.5 High - **Critical:** No - **Weakness (CWE):** [CWE-20](https://cwe.mitre.org/data/definitions/20.html) · [CWE-770](https://cwe.mitre.org/data/definitions/770.html) - **Tags:** [Denial of service](https://agentprime.io/advisories/tag/dos.md) · [CWE-20](https://agentprime.io/advisories/tag/cwe-20.md) - **Published:** 30 Jan 2026 - **Updated:** 25 Feb 2026 - **Reviewed by a person:** No Published by the GitHub Advisory Database at 30 Jan 2026, 15:31 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. ## Affected packages - `io.undertow:undertow-core` (Maven): affected `<2.2.39.Final || >=2.4.0.Alpha1, <2.4.0.Beta1 || >=2.3.0.Alpha1, <2.3.21.Final`; fixed in `2.2.39.Final`, `2.4.0.Beta1`, `2.3.21.Final` ## Machine-written summary Summary written by Claude Haiku from the source advisory. Not reviewed by a person. > Undertow (io.undertow:undertow-core) versions before 2.2.39.Final, from 2.3.0.Alpha1 before 2.3.21.Final, and from 2.4.0.Alpha1 before 2.4.0.Beta1 are affected. An unauthenticated remote client can send a request with very large parameter names to servlets that call getParameterNames(), causing an OutOfMemoryError and a denial of service. Upgrade to 2.2.39.Final, 2.3.21.Final, 2.4.0.Beta1, or later. The source gives few details on workarounds. Written 3 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 (redhat) - **CISA KEV:** Not listed. - **EPSS:** 0.0040, the 34th percentile, on 12 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days. ## Timeline - 30 Jan 2026, 14:25 UTC: [Confirmed by the CVE List](https://www.cve.org/CVERecord?id=CVE-2024-4027) - 30 Jan 2026, 15:16 UTC: [Confirmed by NVD](https://nvd.nist.gov/vuln/detail/CVE-2024-4027) - 31 Oct 2026, 14:21 UTC: First seen by agentprime - 31 Oct 2026, 14:21 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-33hj-rcmx-86mv) ## Sources - [GitHub Advisory Database: GHSA-33hj-rcmx-86mv](https://github.com/advisories/GHSA-33hj-rcmx-86mv) - [OSV: GHSA-33hj-rcmx-86mv](https://osv.dev/vulnerability/GHSA-33hj-rcmx-86mv) - - - - - - - - - - - - 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: .