CVE-2026-47066
Infinite loop in hackney Alt-Svc parsing causes CPU exhaustion.
Is CVE-2026-47066 being exploited?
Not confirmed. CVE-2026-47066 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 0.75% probability of exploitation in the next 30 days.
How severe is CVE-2026-47066?
CVE-2026-47066 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-2026-47066?
Yes. A fix has been recorded for CVE-2026-47066. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-47066 affect?
CVE-2026-47066 affects hackney (Erlang/Elixir HTTP client); versions 2.0.0-beta.1 through 4.0.1. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-47066?
Upgrade to hackney 4.0.1 or later
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
DoS on client via crafted Alt-Svc header; infinite loop, 100% CPU, blocks requests.
Patch when possible
- affected>= 2.0.0-beta.1 and < 4.0.1
- affected>= 408e5fe20302226ea8c74dde2bcbd452d712b5b2 and < e548aba1f97ffa3f4750da7b772998fb78c01894
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.