Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessOpen many concurrent connections to Kore
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DeliverySend POST with oversized first body segment
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ExploitUnsigned underflow wraps content_length past limit
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ExecutionBuffers grow unbounded per worker
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ImpactExhaust worker memory, denial of service
Vulnerability Assessment
| Weakness |
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Integer underflow checks
|
| Exploitation Conditions | No special conditions - remote unauthenticated exploitation against default configurations of the Kore web server/framework before 4.3.0, provided the server accepts request bodies (POST, PUT or DELETE), which is standard HTTP handling. The practical limiting factor is scale rather than access: a single request is harmless, so the attacker must open and sustain many concurrent connections, each sending a first body segment larger than its declared Content-Length, to drive unbounded buffer growth and exhaust worker memory. No authentication, user interaction, or non-default setting is required. The condition is fully removed by upgrading to Kore 4.3.0. |
| Impact | All signals describe a genuine but availability-only threat. The provided CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:N/UI:N, VC:N/VI:N/VA:H) marks this as remotely reachable, low-complexity, unauthenticated, and requiring no user interaction, but with impact confined to availability - no confidentiality or integrity loss, consistent with the described worker-memory exhaustion. The vuln.today decision label is 'this_week', not 'act_now' or 'emergency', so this should be prioritized for near-term patching rather than treated as a fire-drill. No EPSS score, no CISA KEV listing, and no public exploit were provided; absence of these is not evidence of safety, but it indicates no confirmed in-the-wild activity at analysis time. The CVSS vector and the description agree (both point to unauthenticated remote resource exhaustion), so there is no network-vs-local conflict here. The main caveat is tag quality: the input tags label this an 'Authentication Bypass', which is incorrect - the flaw bypasses the http_body_max size limit, not authentication, and the real impact is denial of service, so severity should be read as a DoS risk for internet-facing Kore servers rather than as a breach path. |
| Exploit ScenarioDerived | An attacker opens many concurrent POST, PUT or DELETE connections to an internet-facing Kore server (before 4.3.0), each sending a first body segment larger than its declared Content-Length; an unsigned integer underflow wraps content_length to a huge value, bypassing the http_body_max check. Repeated across many connections, per-connection buffers grow without bound and exhaust the worker process memory, causing denial of service. No public exploit code is identified at time of analysis, though the fix commit (1ff3c0f) publicly reveals the trigger condition. |
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Alert meAnalysisAIv1 – Nov 03, 2026
Memory exhaustion in Kore web server/framework releases before 4.3.0 can be triggered by remote unauthenticated attackers who send first request-body segments larger than the declared Content-Length, bypassing the http_body_max limit and causing unbounded buffer growth. The attack requires sustaining many concurrent POST, PUT, or DELETE connections to exhaust worker memory, so the impact is availability-only; no confidentiality, integrity, or code-execution impact is assessed. No public exploit identified at the time of analysis, and the condition is removed by upgrading to Kore 4.3.0.
RemediationAI
Vendor-released patch: Kore 4.3.0. Upgrade affected deployments to 4.3.0 per https://kore.io/releases/4.3.0; the release incorporates the upstream fix commit 1ff3c0f6f7973dc7fc8bf38369790ef2d8079b3b, which adds the request-body length check in src/http.c and fully removes the bypass. The supplied references do not document a vendor-supported workaround, so no alternative configuration is confirmed to eliminate the condition; the advisory link is https://www.vulncheck.com/advisories/kore-before-4.3.0-integer-underflow-memory-exhaustion-via-http-header-recv.
Affected VersionsENISA
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 1 package in euvd
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Technical ContextAI · show details
Kore is a C-based HTTP server and web application framework. The defect sits in the HTTP request-body accounting path (http_header_recv in src/http.c) and is classified as CWE-191 integer underflow: when actual body bytes exceed the declared Content-Length, the content_length accounting can wrap before the existing http_body_max comparison is enforced, allowing buffers to grow without the configured limit. The upstream fix in commit 1ff3c0f6f7973dc7fc8bf38369790ef2d8079b3b adds a check that the buffered body length (nb->s_off - len) exceeds req->content_length, in addition to the http_body_max check, so an oversized first segment is rejected. The intelligence tags it as Authentication Bypass and Integer Overflow, but the assessed and described impact is a bypass of the http_body_max size limit leading to memory exhaustion, not bypass of authentication or code execution. No CPE strings were supplied, so matching is version-based: Kore before 4.3.0, with 4.3.0-rc5 shown in the referenced source line as a pre-fix snapshot.
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Severity by source
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
Remote, unauthenticated, low-complexity request flooding with no user interaction; impact is memory exhaustion affecting availability only, so C:N/I:N/A:H and scope unchanged.
Primary rating from Vendor (vulncheck).
CVSS VectorVendor: vulncheck
Lifecycle Timeline
2DescriptionCVE.org
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.
Executive ViewAI
Kore web server versions prior to 4.3.0 are vulnerable to a memory exhaustion flaw that can be triggered by unauthenticated remote attackers, potentially causing service outages for applications relying on this framework. While no public exploit has been identified, the availability-only impact means any downtime could disrupt customer-facing services and internal operations, making it a concern for leadership due to potential reputational and financial consequences.
No vendor-released patch identified at time of analysis; interim mitigations include rate limiting concurrent POST/PUT/DELETE connections, enforcing strict Content-Length validation at the network edge, deploying memory monitoring and auto-scaling to absorb exhaustion attempts, and isolating vulnerable services behind a reverse proxy with request size limits.
Threat Intelligence Overview
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.
EUVD-2026-116585
GHSA-f33j-xw62-gm9f
NVD
CVE.org
Exploit-DB