CVE-2026-15076
Vert.x Web Client accepts attacker-set cookies for arbitrary domains, enabling account takeover.
Is CVE-2026-15076 being exploited?
Not confirmed. CVE-2026-15076 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 0.20% probability of exploitation in the next 30 days.
How severe is CVE-2026-15076?
CVE-2026-15076 is rated High with a CVSS score of 8.2. 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-2026-15076?
Yes. A fix has been recorded for CVE-2026-15076. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-15076 affect?
CVE-2026-15076 affects Eclipse Vert.x Web Client <=4.5.29 (4.x), Eclipse Vert.x Web Client <=5.1.4 (5.x). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-15076?
Upgrade WebClient to versions >4.5.29 or >5.1.4 and validate Set-Cookie domain checks.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Attacker controlling a contacted server can inject cookies for third-party domains; victim app will send them, enabling account takeover, unauthorized transactions, and data exposure.
Immediate action required
- affected>= 4.0.0 and <= 4.5.29
- affected>= 5.0.0 and <= 5.1.4
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.