Kore before 4.3.0 contains an integer underflow vulnerability in HTTP request body handling that allows
Source GCVE Database
Not known to be exploited · CVSS 8.7 High : upgrade to 4.3.0 soon.
Data as of 4 Nov 2026, 02:00 UTC
Thin evidence
One scorer or none| CNA (VulnCheck) | CVSS 4.0 | 8.7 |
|---|---|---|
| CNA (VulnCheck) | CVSS 3.1 | 7.5 |
- Patch
- Available – fixed in 4.3.0
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 3 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 3 Nov 2026.
What to do
Upgrade kore to 4.3.0.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| jorisvinkkore | Affected
| Fixed in
|
GitHubkorepkg:github/koreOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
If you cannot patch yet, consider limiting the number of concurrent POST, PUT, or DELETE requests or implementing network-level protections to mitigate potential memory exhaustion.
Description
Kore versions prior to 4.3.0 have an integer underflow vulnerability in the handling of HTTP request bodies. This flaw allows unauthenticated attackers to bypass the http_body_max limit by sending more body bytes than declared. By sending oversized first segments across many concurrent POST, PUT, or DELETE requests, attackers can cause the content_length value to wrap, leading to unbounded buffer growth and exhaustion of worker memory.
References
- nvd.nist.gov/vuln/detail/CVE-2026-121727 (opens in a new tab)
- github.com/jorisvink/kore/commit/1ff3c0f6f7973dc7fc8bf38369790ef2d8079b3b (opens in a new tab)
- github.com/jorisvink/kore (opens in a new tab)
- github.com/jorisvink/kore/blob/4.3.0-rc5/src/http.c (opens in a new tab)
- kore.io/releases/4.3.0 (opens in a new tab)
- vulncheck.com/advisories/kore-before-4.3.0-integer-underflow-memory-exhaustion-via-http-header-recv (opens in a new tab)