Enterprise-grade IBM WebSphere is widely used; high-severity smuggling can expose sessions/data and bypass caches, impacting many organizations.
CVE-2026-15064
HTTP response smuggling in IBM WebSphere via non-standard HTTP version tokens
Is CVE-2026-15064 being exploited?
Not confirmed. CVE-2026-15064 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.22% probability of exploitation in the next 30 days.
How severe is CVE-2026-15064?
CVE-2026-15064 is rated High with a CVSS score of 8.7. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-15064?
Yes. A fix has been recorded for CVE-2026-15064. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-15064 affect?
CVE-2026-15064 affects IBM WebSphere Application Server 9.0, IBM WebSphere Application Server 8.5, IBM WebSphere Liberty 17.0.0.3 - 26.0.0.7. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-15064?
Apply vendor fixes when released; block/normalize non-standard HTTP version tokens at edge/WAF.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Allows request/response splitting, web cache poisoning, session hijack and unauthorized data access via crafted HTTP requests.
Immediate action required
- affected9.0
- affected8.5
- affected>= 17.0.0.3 and <= 26.0.0.7
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.