Critical TLS hostname verification bypass in a widely used Apache HttpComponents async client; enables broad MITM impersonation across Java applications.
CVE-2026-71290
Async HttpClient 5.4+ bypasses TLS hostname verification, enabling MITM server impersonation.
Is CVE-2026-71290 being exploited?
Not confirmed. CVE-2026-71290 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 0.24% probability of exploitation in the next 30 days.
How severe is CVE-2026-71290?
CVE-2026-71290 is rated Critical with a CVSS score of 9.1. 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-2026-71290?
Yes. A fix has been recorded for CVE-2026-71290. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-71290 affect?
CVE-2026-71290 affects Apache HttpComponents HttpClient (async) 5.4 - 5.6.3, Java applications using async HttpClient. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-71290?
Upgrade async HttpClient to 5.6.4+; if not possible, avoid async client or use classic HttpClient until patched.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
TLS hostname verification bypass in async HttpClient lets a MITM attacker impersonate servers to intercept/modify traffic, steal credentials and session data.
Immediate action required
- affected>= 5.4-alpha and <= 5.6.3
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.