CVE-2026-33871
Netty HTTP/2 DoS via unlimited CONTINUATION frames (pre-4.1.132.Final, 4.2.10.Final).
Is CVE-2026-33871 being exploited?
Not confirmed. CVE-2026-33871 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 1.1% probability of exploitation in the next 30 days.
How severe is CVE-2026-33871?
CVE-2026-33871 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-2026-33871?
Yes. A fix has been recorded for CVE-2026-33871. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-33871 affect?
CVE-2026-33871 affects Netty 4.1.x before 4.1.132.Final, Netty 4.2.x before 4.2.10.Final. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-33871?
Upgrade to Netty 4.1.132.Final or 4.2.10.Final or newer.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote DoS: flood of CONTINUATION frames causes CPU exhaustion and server unavailability.
Immediate action required
- affected< 4.1.132.Final
- affected>= 4.2.0.Alpha1 and < 4.2.10.Final
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.