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vLLM EUVDEUVD-2026-107001

| CVE-2026-114050 HIGH
Insufficient Verification of Data Authenticity (CWE-345)
2026-10-21 VulnCheck GHSA-hfwf-hgvp-4rr8
7.1
CVSS 4.0 · Vendor: VulnCheck
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Reach network-exposed vLLM inference API
  2. Exploit
    Send request with forged multimodal UUID
  3. Execution
    Desync P0/P1 processor caches on cache hit
  4. Impact
    Trigger fatal token-placeholder mismatch, kill serving instance

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A08:2025 - Software or Data Integrity Failures
ASVS 5.0
V15 - Secure Coding and Architecture Data authenticity verification
Exploitation Conditions

The target must be a vLLM instance (before 0.31.0) serving a multimodal model, since the flaw lives in how the multimodal processor caches (P0/P1) key entries on client-supplied UUIDs; a text-only deployment is not affected. Exploitation requires sending inference requests that reuse or forge a multimodal UUID so that a cache hit occurs against mismatched content, with no consistency check performed. Limiting factors: the deployment must expose the multimodal inference API to the attacker, and the authentication requirement is not confirmed from available data - the description states unauthenticated access while the CVSS vector indicates PR:L, so whether an API key or token is needed depends on how the operator configured the endpoint (vLLM's default server has no authentication).

Impact

This is a denial-of-service vulnerability (CWE-345, insufficient verification of data authenticity) in vLLM's handling of client-supplied multimodal UUIDs. The vendor CVSS 4.0 vector (CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H) scores 7.1 and reflects a network-reachable, low-complexity attack with high availability impact but zero confidentiality or integrity impact - consistent with a service-crash bug rather than code execution or data exposure. A key conflict exists in the source data: the description explicitly states 'Unauthenticated attackers,' yet the CVSS vector specifies PR:L (authenticated/low privilege) - verify with vendor, as this materially changes exposure (vLLM's OpenAI-compatible server commonly runs without authentication by default, which would support the unauthenticated reading and arguably warrants PR:N). No EPSS score, CISA KEV listing, or public POC was provided in the input; therefore there is no public exploit identified at time of analysis. Real-world priority is moderate: the impact ceiling is availability-only (a restartable crash, not RCE or data theft), so despite easy triggering this is a reliability/resilience risk rather than a critical breach vector. It matters most for production inference endpoints where a single forged request can take down the entire serving instance.

Exploit ScenarioDerived

An attacker with network access to a vLLM inference endpoint serving a multimodal model sends crafted requests that reuse or forge the client-supplied multimodal UUID, which vLLM trusts verbatim as a cache key without any consistency check. This desynchronizes the P0/P1 processor caches, producing a fatal token-placeholder mismatch that crashes the entire serving process and denies service to all clients until an operator restarts it. No public exploit code was identified in the provided data.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.2% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 21, 2026

Denial of service in vLLM before 0.31.0 allows remote attackers to crash the entire serving instance by forging or reusing a client-supplied multimodal UUID so the P0/P1 processor caches disagree on token placeholders and hit a fatal mismatch. The flaw is reachable only when the deployment serves a multimodal model and exposes the multimodal inference API; text-only vLLM deployments are not affected. No public exploit was identified at time of analysis, and authentication requirements are conflicting in the supplied data: the CVSS 4.0 vector is PR:L while the independent assessment uses PR:N and the description says unauthenticated, so exposure depends on whether the endpoint is protected (vLLM's default server has no authentication per the assessment).

RemediationAI

Vendor-released patch: vLLM 0.31.0 or later, which is the fix version identified by the 'before 0.31.0' affected range; see https://github.com/vllm-project/vllm/security/advisories/GHSA-p92p-rxj5-7p2x. If immediate upgrade is not possible, remove the attack surface by running text-only models or disabling multimodal inference endpoints when multimodal serving is not required, accepting loss of multimodal functionality. Otherwise, place the inference API behind an authenticating reverse proxy and restrict it to trusted clients, noting that this reduces exposure but does not fix cache desynchronization for clients that are allowed to submit multimodal requests; vLLM's default server has no authentication per the assessment. Add health checks and automatic restart or per-tenant instance isolation to limit outage duration and blast radius, but treat these as containment rather than remediation.

Affected VersionsENISA

vllm 0 <0.31.0

Affected Packages

euvd vllm fix: 0.31.0

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

vLLM is an LLM serving engine that uses processor caches (P0/P1) to speed up multimodal request handling. In affected versions, the server takes a client-supplied multimodal UUID verbatim as the cache identity and performs no consistency check when a cache hit occurs, which is CWE-345 insufficient verification of data authenticity. An attacker who can submit inference requests can desynchronize the P0/P1 caches by causing a hit against mismatched content, leading to a fatal token-placeholder mismatch and termination of the serving process. The CPE cpe:2.3:a:vllm-project:vllm:*:*:*:*:*:*:*:* confirms the affected product is vLLM prior to 0.31.0. The CVSS 4.0 vector AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N rates only availability impact as High; the independent CVSS 3.1 assessment agrees on availability-only impact but uses PR:N, so the effective authentication prerequisite is deployment-dependent.

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Severity by source

Vendor (VulnCheck) PRIMARY 7.1 HIGH
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
vuln.today AI 7.5 HIGH

Network-reachable, low-complexity forged request with no user interaction; PR:N follows the description's 'unauthenticated' claim and vLLM's default no-auth server, though vendor used PR:L; impact is availability-only (A:H), no scope change.

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Primary rating from Vendor (VulnCheck).

CVSS VectorVendor: VulnCheck

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
Low
User Interaction
None
Vulnerable system: Confidentiality
None
Vulnerable system: Integrity
None
Vulnerable system: Availability
High
Subsequent system: Confidentiality
None
Subsequent system: Integrity
None
Subsequent system: Availability
None

Lifecycle Timeline

2
Patch available
Oct 21, 2026 - 02:01 EUVD
CVE Published
Oct 21, 2026 - 00:36 cve.org
HIGH 7.1

DescriptionCVE.org

vLLM before 0.31.0 uses a client-supplied multimodal uuid verbatim as cache identity with no consistency check on cache hits, allowing engine crashes. Unauthenticated attackers can desynchronize the P0/P1 processor caches to trigger a fatal token-placeholder mismatch, killing the entire serving instance until restarted.

Technical POC Analysis

CWE-345 (Insufficient Verification of Data Authenticity), specifically a client-controlled cache key with an unvalidated cache-hit path.

Full technical POC analysis - root cause, step-by-step exploitation and patch breakdown - is part of the Pro and Business plans.

Executive ViewAI

Why It Matters

vLLM deployments that expose multimodal inference APIs face a high-severity availability risk: a crafted request can crash the entire model-serving instance, disrupting every application and user that depends on that endpoint. Text-only vLLM services are not affected, but production or customer-facing multimodal inference should be prioritized because no vendor patch was available at analysis time and endpoint protection may vary. No public exploit identified at time of analysis, so near-term risk is driven mainly by exposed API surface and the absence of a patch.

Business Impact: High
Compensating Controls

No vendor-released patch identified at time of analysis. Interim mitigations include disabling or restricting the multimodal inference API, requiring authentication and network allowlisting at a gateway, validating and rejecting forged or replayed multimodal UUIDs, rate-limiting and monitoring crash patterns, and isolating multimodal serving until upgrade to vLLM 0.31.0 or later is available.

Threat Intelligence Overview

EPSS Score
0.2%
Top 94% exploitable
Prevalence
High
vLLM is the dominant open-source LLM inference/serving engine in AI deployments
Data Quality
6 sources
Confidence: High

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.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS 0.2%
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact
High
Technical Impact
Partial

Priority Score

36
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +36
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

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