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agentverus-scanner EUVDEUVD-2026-70226

| CVE-2026-84811 HIGH
Protection Mechanism Failure (CWE-693)
2026-09-02 disclosure@vulncheck.com GHSA-7r9q-g8p5-w7pp
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. Recon
    Craft malicious .pyc in __pycache__ alongside benign .py source
  2. Delivery
    Publish poisoned package to accessible Python registry
  3. Exploit
    Victim CI/CD scans package with agentverus-scanner
  4. Install
    Scanner skips bytecode; issues CERTIFIED verdict
  5. C2
    Victim approves and installs package
  6. Execute
    CPython resolves .pyc over .py at import
  7. Impact
    Malicious bytecode executes in victim runtime

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A06:2025 - Insecure Design
ASVS 5.0
V15 - Secure Coding and Architecture Protection mechanism completeness
Exploitation Conditions

Exploitation requires that the victim organization uses agentverus-scanner as a gate for approving Python packages and that the attacker can introduce a package into a registry or path the scanner evaluates. The malicious package must include at least one __pycache__ directory with a valid .pyc file whose bytecode diverges from the accompanying .py source. CPython must be present in the execution environment (any CPython 3.x version that validates the .pyc header). No authentication or elevated privilege is required to craft or distribute the malicious package. Exploitation is limited to environments that (a) run agentverus-scanner v0.8.1 or an unpatched version, (b) treat its CERTIFIED verdict as sufficient approval for package import, and (c) subsequently import the approved package in a live Python runtime.

Impact

The CVSS 4.0 score of 7.1 (AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:N) captures only the scanner's own system impact - a false-positive CERTIFIED verdict - and omits subsequent system RCE, which is the actual realized harm. Real-world risk is materially higher: an attacker with no privileges can publish a poisoned package to any Python registry, pass scanner gate checks, and achieve arbitrary code execution in every environment that trusts the scanner's verdict. The attack is low-complexity and requires only passive user interaction (a normal import). No KEV listing and no confirmed public exploit code mitigate urgency, but the bypass technique is fully described in the VulnCheck advisory. EPSS data is absent from available signals. The primary risk limiter is the scanner's niche deployment footprint; organizations that have integrated agentverus-scanner into CI/CD or supply-chain vetting pipelines face meaningful supply-chain RCE exposure.

Exploit ScenarioDerived

An attacker publishes a PyPI package containing a harmless math_utils.py alongside a __pycache__/math_utils.cpython-312.pyc that, when imported, beacons out and opens a reverse shell. A victim organization's CI/CD pipeline scans the package with agentverus-scanner, receives a CERTIFIED verdict with high trust scores, approves the dependency, and deploys it - triggering code execution at the first import in staging or production.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
No patch listed yet 0.3% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 02, 2026

Python bytecode scanning gap in agentverus-scanner allows supply-chain attackers to smuggle malicious __pycache__ .pyc files past the tool's static and semantic analysis engines, which only inspect source .py files in companion code directories. Packages carrying malicious bytecode alongside benign source receive a CERTIFIED verdict with elevated trust scores, causing downstream environments that trust the scanner to silently execute attacker-controlled code on import. No public exploit code has been identified at time of analysis, but the VulnCheck advisory and GitHub issue #27 document the bypass technique in sufficient detail for reproduction.

RemediationAI

No vendor-released patched version is independently confirmed at time of analysis. Upstream fix availability should be tracked via GitHub issue #27 (https://github.com/agentverus/agentverus-scanner/issues/27) and the VulnCheck advisory (https://www.vulncheck.com/advisories/agentverus-scanner-companion-code-analysis-bypass-via-excluded-python-bytecode). As a compensating control, organizations should extend scanner invocations to explicitly enumerate and disassemble .pyc files in all __pycache__ subdirectories using tools such as uncompyle6 or pycdc before trusting any CERTIFIED verdict. A second compensating control is to delete or strip __pycache__ directories from all third-party packages before import, forcing CPython to recompile from source - this adds build latency but closes the bytecode substitution vector. Do not treat agentverus-scanner CERTIFIED verdicts as authoritative for packages containing __pycache__ entries until a patched release confirms the coverage gap is closed.

Affected VersionsENISA

agentverus-scanner 0 ≤0.8.1

Affected Packages

euvd agentverus_scanner no fix

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

agentverus-scanner (v0.8.1) performs companion-code analysis to inspect Python packages distributed alongside compiled components. The flaw lies in companion-code.ts and the semantic analyzer (semantic.ts): neither stage enumerates or evaluates .pyc files stored in __pycache__ subdirectories. CPython resolves compiled bytecode over source files when __pycache__ entries are present and timestamp/hash-validated, so a package can ship a benign top-level foo.py while __pycache__/foo.cpython-3x.pyc executes entirely different logic at import time. CWE-693 (Protection Mechanism Failure) is the correct classification: the scanner's protection mechanism is bypassed because its coverage model omits a legitimate Python execution artifact.

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Severity by source

Vendor (vulncheck) PRIMARY 7.1 HIGH
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
vuln.today AI 9.6 CRITICAL

Network-distributed malicious package; low complexity; no attacker privileges; victim must import package (UI:R); scope changes to victim runtime where RCE achieves full C/I/A impact.

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

Primary rating from Vendor (vulncheck).

CVSS VectorVendor: vulncheck

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

DescriptionCVE.org

agentverus-scanner fails to analyze compiled Python bytecode files in companion code directories, allowing attackers to bypass security scanning by shipping malicious __pycache__ entries alongside benign source files. Attackers can execute arbitrary Python bytecode on import while the scanner reports a CERTIFIED verdict with high trust scores in both static and semantic analysis modes.

Executive ViewAI

Why It Matters

agentverus-scanner contains a scanning gap that allows attackers to bypass its analysis engines by embedding malicious Python bytecode (.pyc files) in packages, which receive CERTIFIED verdicts and silent code execution upon import in downstream environments. This vulnerability directly undermines supply-chain security controls that organizations depend on for trusted dependency assessment. Development teams and DevOps using this scanner for package validation face potential code execution in their environments without detection.

Business Impact: High
Compensating Controls

No vendor-released patch identified at time of analysis. Interim mitigations: Manually inspect __pycache__ directories in dependencies scanned by agentverus-scanner; disable automated trust/elevated scoring based on CERTIFIED verdicts from this tool; require manual code review before trusting scanner-approved packages; implement supplementary SCA tooling with bytecode inspection capabilities; maintain signed software provenance records independent of this scanner's assessments.

Threat Intelligence Overview

EPSS Score
0.3%
Top 79% exploitable
Prevalence
Rare
niche AI/supply-chain security scanner, early-version (v0.8.1)
Data Quality
7 sources
Confidence: High
EUVD NVD CVE.org EPSS Vulnrichment GitHub VulDB

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 0.3%
Patch available No
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
Yes
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

Remote Code Execution represents the critical moment when an attacker successfully runs arbitrary code on a target system without physical access.

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