CyberSecBulletin
CVE-2026-8646NVD status: Analyzed

WebSphere Application Server: Inconsistent Interpretation of HTTP Requests

Published Updated By the CyberSecBulletin desk

CVE-2026-8646 is a critical-severity inconsistent interpretation of HTTP requests vulnerability in WebSphere Application Server from IBM, with a CVSS 3.1 base score of 9.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected WebSphere Application Server versions: 9.0.0 through 7.0.2 Interim Fix 035; 8.5.0 through 7.0.3 Interim Fix 017. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.59% chance of exploitation within 30 days, which is low compared with other CVEs.

Patch this week

Critical severity: a successful attack would have severe impact.

What to do

  1. Check which version of WebSphere Application Server you run against the affected versions below, and install the vendor's latest release.
  2. Read the advisory on ibm.com for workarounds and exact fixed builds.
  3. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
IBMWebSphere Application Server9.0.0 through 7.0.2 Interim Fix 035; 8.5.0 through 7.0.3 Interim Fix 017Not stated
IBMWebSphere Application Server - Liberty17.0.0.3 through 26.0.0.6Not stated

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
NoneAvailability is not affected.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.17.4HighCNA (us.ibm.com)
CVSS 3.19.1CriticalNVD

Official description

IBM WebSphere Application Server 9.0 and 8.5 and IBM WebSphere Application Server - Liberty 17.0.0.3 through 26.0.0.6 are vulnerable to HTTP request smuggling. A remote attacker could smuggle a specially crafted request to the application server thereby allowing the attacker to bypass security controls, spoof identity, escalate privilege, and expose sensitive information.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Inconsistent Interpretation of HTTP Requests

The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.

How developers prevent this class of flaw

  • Use a web server that employs a strict HTTP parsing procedure, such as Apache.
  • Terminate the client session after each request.

More Inconsistent Interpretation of HTTP Requests vulnerabilities (CWE-444)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in WebSphere Application Server

All WebSphere Application Server vulnerabilities

Recent Inconsistent Interpretation of HTTP Requests vulnerabilities

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