CVE-2026-121727
Kore before 4.3.0 Integer Underflow Memory Exhaustion via http_header_recv()
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.
Fixes and workarounds
Fix
The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.
Source: CNA: VulnCheckAffected products and versions
| Product | Versions | Authority |
|---|---|---|
| kore jorisvink jorisvink/kore
github |
≥ 0; < 4.3.0 (affected, semver)
Other versions: unaffected |
CNA: VulnCheck |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 4.0 / 8.7 high |
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N | CNA: VulnCheck |
| 3.1 / 7.5 high |
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | CNA: VulnCheck |
| 4.0 / 8.7 high |
CVSS: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 | NVD: [email protected] |
| 3.1 / 7.5 high |
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | NVD: [email protected] |
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://github.com/jorisvink/kore/commit/1ff3c0f6f7973dc7fc8bf38369790ef2d8079b3bCNA: VulnCheck · patch
- https://github.com/jorisvink/koreCNA: VulnCheck · product
- https://kore.io/releases/4.3.0CNA: VulnCheck · release-notes
- https://github.com/jorisvink/kore/blob/4.3.0-rc5/src/http.c#L934CNA: VulnCheck · technical-description
- https://www.vulncheck.com/advisories/kore-before-4.3.0-integer-underflow-memory-exhaustion-via-http-header-recvCNA: VulnCheck · third-party-advisory
- https://github.com/jorisvink/kore[email protected]
- https://github.com/jorisvink/kore/blob/4.3.0-rc5/src/http.c#L934[email protected]
- https://github.com/jorisvink/kore/commit/1ff3c0f6f7973dc7fc8bf38369790ef2d8079b3b[email protected]
- https://kore.io/releases/4.3.0[email protected]
- https://www.vulncheck.com/advisories/kore-before-4.3.0-integer-underflow-memory-exhaustion-via-http-header-recv[email protected]
For agents and automation
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