CVE-2026-121727 Kore before 4.3.0 Integer Underflow Memory Exhaustion via http_header_recv()

High 8.7 Published 3 Nov 2026 Updated 9 Nov 2026

Exploited in the wild: Not known
Fix: None listed

What is CVE-2026-121727?

CVE-2026-121727 is a high-severity vulnerability in jorisvink kore, published on 3 Nov 2026.

Official description

Kore before 4.3.0 contains an integer underflow vulnerability in HTTP request body handling that allows unauthenticated attackers to bypass http_body_max by sending more body bytes than declared. Attackers can send oversized first segments over many concurrent POST, PUT or DELETE connections, wrapping content_length to grow buffers unbounded and exhaust worker memory.

Weakness: CWE-191

Which versions are affected by CVE-2026-121727?

How do I fix CVE-2026-121727?

No fix has been published for CVE-2026-121727 yet. Limit exposure of the affected software until one is available.

Is CVE-2026-121727 being exploited?

There is no known exploitation of CVE-2026-121727 in the wild and no public exploit code.

Sources

Also known as DEBIAN-CVE-2026-121727, GHSA-f33j-xw62-gm9f, UBUNTU-CVE-2026-121727.