CVE-2026-121727

Kore before 4.3.0 Integer Underflow Memory Exhaustion via http_header_recv()

8.7 High

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.

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: None

What an attacker can affect

Confidentiality: None
Integrity: None
Availability: High

Exploit likelihood

0.39%Unchanged since Nov 4, 2026

What each source reports

CVE List Score used 8.7

Kore before 4.3.0 Integer Underflow Memory Exhaustion via http_header_recv()

Record: CVE-2026-121727
CVSS 4.0: 8.7 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness: CWE-191
Updated: 2026-11-03

EUVDEUVD-2026-116585 8.7

Record: EUVD-2026-116585
CVSS 4.0: 8.7 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Updated: 2026-11-04

GitHub AdvisoriesGHSA-f33j-xw62-gm9f 8.7

Kore before 4.3.0 contains an integer underflow vulnerability in HTTP request body handling that...

Record: GHSA-f33j-xw62-gm9f
CVSS 4.0: 8.7 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness: CWE-191
Updated: 2026-11-04

NVD 8.7

Record: CVE-2026-121727
CVSS 4.0: 8.7 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness: CWE-191
Updated: 2026-11-04

OSV 8.7

Kore before 4.3.0 Integer Underflow Memory Exhaustion via http_header_recv()

Record: CVE-2026-121727
CVSS 4.0: 8.7 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Weakness: CWE-191
Updated: 2026-11-05

OSVDEBIAN-CVE-2026-121727 7.5

Record: DEBIAN-CVE-2026-121727
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated: 2026-11-06

OSVUBUNTU-CVE-2026-121727 8.7

Record: UBUNTU-CVE-2026-121727
CVSS 4.0: 8.7 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated: 2026-11-05

Affected products

jorisvink kore

Affected packages

Affected packages
Package	Affected	Fixed
`kore` Debian:12	All versions, plus listed versions 4.1.0-64.2.3-14.2.3-2	None known
`kore` Debian:14	All versions, plus listed versions 1.2.3-11.2.3-21.2.3-31.2.3-41.2.3-5 Show 18 moreShow less 2.0.0-12.0.0-22.0.0-32.0.0-43.3.1-14.0.1-14.0.1-24.0.1-34.0.1-44.0.1-54.1.0-14.1.0-24.1.0-34.1.0-44.1.0-54.1.0-64.2.3-14.2.3-2	None known
`kore` Ubuntu:16.04:LTS	All versions, plus listed versions 1.2.3-11.2.3-21.2.3-31.2.3-41.2.3-5	None known
`kore` Ubuntu:20.04:LTS	All versions, plus listed versions 2.0.0-43.3.1-1	None known
`kore` Ubuntu:22.04:LTS	All versions, plus listed versions 4.1.0-34.1.0-44.1.0-4ubuntu14.1.0-6	None known
`kore` Ubuntu:24.04:LTS	All versions, plus listed versions 4.1.0-6	None known
`kore` Ubuntu:26.10	All versions, plus listed versions 4.2.3-24.2.3-2build1	None known
`kore` Ubuntu:26.04:LTS	All versions, plus listed versions 4.2.3-2	None known

History

History
Recorded	Changed	Sources
Nov 6, 2026	affected, aliases, references	OSV
Nov 5, 2026	affected, aliases, references	OSV
Nov 4, 2026	references	OSV
Nov 4, 2026	published	EUVD, NVD
Nov 4, 2026	aliases, published, references	EUVD, GitHub Advisories
Nov 4, 2026	first indexed	CVE List

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-121727 is a high vulnerability (CVSS 8.7) in Jorisvink Kore, published November 3, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.39%, the 33rd percentile. No source names a fixed version.

References

Show 5 moreShow less