# CVE-2026-8620 — IBM Web Server Plug-ins for WebSphere Application Server and WebSphere Liberty

> As of 2026-05-27, CVE-2026-8620 is a HIGH-severity vulnerability in IBM Web Server Plug-ins for WebSphere Application Server and WebSphere Liberty, CVSS v3.1 7.5, EPSS 0.3% (29.0th percentile). Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2026-8620, most recently “IBM WebSphere Application Server & Liberty Web Server Plug-ins Unauthenticated RCE and HTTP Request Smuggling (CVE-2026-8633, CVE-2026-8620)”.

**Last updated:** 2026-05-27

## What is CVE-2026-8620?

IBM Web Server Plug-ins for WebSphere Application Server and WebSphere Liberty 8.5, 9.0 IBM WebSphere Application Server and WebSphere Application Server Liberty are vulnerable to HTTP request smuggling in the Web Server Plug-ins through a specially crafted request.

The record classifies CVE-2026-8620 under weakness class [CWE-444](https://intel.threadlinqs.com/cwe/CWE-444). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on confidentiality. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 138 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 7.5 — HIGH (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:L/A:N`)
- **EPSS (FIRST):** 0.3% probability of exploitation in the next 30 days, higher than 29.0% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 4.9/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-05-26, last modified 2026-05-27

## Is CVE-2026-8620 being exploited?

It currently carries a trending score of 12 in the Threadlinqs vulnerability feed.

## Affected products and versions

- [IBM](https://intel.threadlinqs.com/vendors/ibm): Web Server Plug-ins for WebSphere Application Server and WebSphere Liberty

## How to fix CVE-2026-8620

No vendor patch reference has been recorded for CVE-2026-8620 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-8620

1 tracked threat in the Threadlinqs corpus references CVE-2026-8620, either in the campaign’s CVE list or as an indicator on the campaign record.

- [IBM WebSphere Application Server & Liberty Web Server Plug-ins Unauthenticated RCE and HTTP Request Smuggling (CVE-2026-8633, CVE-2026-8620)](https://intel.threadlinqs.com/threat/TL-2026-0650) — CRITICAL · 2026-06-01

## Sources

Enriched from CVE.org, FIRST EPSS, GitHub Security Advisories. Last verified by Threadlinqs on 2026-10-10.

**Vendor advisory and patch**

- [ibm.com — vendor advisory](https://www.ibm.com/support/pages/node/7274072)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-8620
Full detection coverage and IOCs for threats exploiting CVE-2026-8620 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp