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BOSH Director EUVDEUVD-2026-32108

| CVE-2026-41704 MEDIUM
Improper Access Control (CWE-284)
2026-05-27 security@vmware.com GHSA-mhvf-vxjh-cwwp
6.8
CVSS 4.0 · Vendor: vmware
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Attack ChainAIDerived

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

  1. Access
    Compromise BOSH-managed VM with high privileges
  2. Delivery
    Gain publish access to NATS message bus
  3. Exploit
    Craft malicious NATS reply containing arbitrary target blob IDs
  4. Execution
    Director AgentClient processes reply without ID ownership validation
  5. Persist
    ResourceManager calls blobstore.delete() on shared Director blobstore
  6. Impact
    Targeted deployment artifacts deleted, causing availability failures in dependent deployments

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V8 - Authorization Access control enforcement
MITRE ATT&CK

1 technique across 1 tactic: Defense Evasion

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Exploitation requires that the attacker has already achieved high-privileged access (PR:H per CVSS 4.0 vector) on a BOSH-managed VM sufficient to publish crafted NATS reply messages that the Director's AgentClient will process. The attack vector is local (AV:L), meaning the attacker must be operating from within the BOSH-managed infrastructure with access to the NATS message bus - this is not an internet-facing attack surface. Attack complexity is rated High (AC:H), indicating that conditions beyond mere VM access are required, such as precise timing of the crafted reply within an active NATS exchange or overcoming other environmental constraints specific to the Director's message processing loop. This vulnerability does not enable initial access and provides no confidentiality benefit; it is exclusively a post-compromise destructive capability. Limiting factors include: the mandatory prior high-privilege VM compromise, High attack complexity reducing reliable exploitation, and the absence of any network-reachable entry point. Environments with strict NATS access controls or VM isolation significantly reduce the realistic attack surface.

Impact

All available signals converge on a moderate, post-compromise risk profile rather than a critical mass-exploitation threat. The CVSS 4.0 score of 6.8 reflects the constrained attack geometry: AV:L (local, requiring presence within BOSH-managed infrastructure), AC:H (high attack complexity, implying non-trivial timing or environmental conditions), and PR:H (high privileges required, meaning the attacker must already control a BOSH-managed VM with elevated access). EPSS at 0.01% (1st percentile) is consistent with the SSVC determination of Exploitation: none and Automatable: no - this is not a target for opportunistic or automated mass exploitation. The impact profile is asymmetric: no confidentiality loss (VC:N, SC:N), high integrity impact to the vulnerable system (VI:H - arbitrary blob deletion), and high availability impact to subsequent systems (SA:H - dependent deployments break when blobs are missing). The 'Authentication Bypass' tag reflects the absent blobstore access control, but this label can be misleading in isolation: exploitation is still gated behind a prior full VM compromise at high privilege. This vulnerability functions as a post-compromise lateral damage enabler within an already partially-compromised BOSH environment, not an initial access vector. No conflicting signals were identified; CVSS, EPSS, and SSVC are internally consistent.

Exploit ScenarioDerived

An attacker who has gained root or equivalent high-privileged access on a BOSH-managed VM crafts a malicious NATS reply message containing a targeted blob ID in the compile_log_id or blobstore_id field, chosen to match a critical deployment artifact such as a compiled package or release binary. The BOSH Director's AgentClient accepts the reply and passes the ID directly to ResourceManager, which calls blobstore.delete() without any ownership or format check, permanently removing the artifact from the shared blobstore. Downstream deployments or pipelines referencing the deleted blob then fail, producing availability impact across the BOSH environment. No public POC exists at time of analysis.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – May 27, 2026

Arbitrary blobstore deletion in BOSH Director allows a compromised, high-privileged BOSH-managed VM to delete any object from the shared Director blobstore by injecting crafted NATS reply messages. All BOSH Director versions prior to v282.1.12 are affected, with the root cause being a complete absence of UUID-format validation, ownership checks, and namespace prefixing in ResourceManager before executing blobstore.delete(). An attacker leveraging this post-compromise path can corrupt or destroy deployment artifacts, compiled packages, and release binaries relied upon by dependent deployments, producing cascading availability failures across the BOSH environment. No public exploit or active exploitation has been identified at time of analysis; SSVC confirms exploitation status as none.

RemediationAI

The primary fix is to upgrade BOSH Director to v282.1.12 or later, which resolves the missing ownership and format validation in ResourceManager's blobstore deletion path. The fix version v282.1.12 is confirmed by both the Cloud Foundry vendor advisory and the ENISA EUVD record (EUVD-2026-32108); the advisory is at https://www.cloudfoundry.org/blog/cve-2026-41704-compromised-vm-can-make-arbitrary-blobstore-deletes/. If immediate patching is not feasible, a targeted compensating control is to implement network segmentation restricting NATS message bus publish access so that only authorized BOSH agents can send replies the Director processes - this limits the blast radius if a VM is compromised, though it requires careful testing as NATS communication is central to normal BOSH agent operation and misconfiguration will disrupt deployments. Additionally, enabling blobstore access logging and alerting on anomalous deletion volume can provide detection coverage for active exploitation attempts. No workaround eliminates the root cause; patching to v282.1.12 is the only confirmed remediation.

Affected VersionsENISA

BOSH Director 0 <282.1.12

Affected Packages

euvd bosh_director fix: 282.1.12

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

BOSH is a Cloud Foundry/VMware cloud infrastructure automation platform that manages VMs via a NATS message bus. The Director's AgentClient#handle_method (lines 264-303) processes every inbound NATS reply. Two distinct code paths both resolve to the same vulnerable sink: inject_compile_log (line 273) reads response['value']['result']['compile_log_id'] and calls download_and_delete_blob, while format_exception (lines 308-325) reads exception['blobstore_id'] and calls the same helper. The download_and_delete_blob helper (lines 344-349) invokes ResourceManager#get_resource and, in an ensure block, ResourceManager#delete_resource. ResourceManager (resource_manager.rb:62-70) calls blobstore.delete(id) directly on the single shared Director blobstore instance with no UUID-format check, no ownership verification, and no namespace prefix enforcement. CWE-284 (Improper Access Control) accurately describes the root cause: the system permits an operation - arbitrary blob deletion - that should require proof of ownership or scope but has no such gate.

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Severity by source

Vendor (vmware) PRIMARY 6.8 MEDIUM
CVSS:4.0/AV:L/AC:H/AT:N/PR:H/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:H

Primary rating from Vendor (vmware) · only source for this CVE.

CVSS VectorVendor: vmware

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

Lifecycle Timeline

1
Patch available
May 27, 2026 - 19:46 EUVD

DescriptionCVE.org

AgentClient#handle_method (lines 264-303) processes every NATS reply. It calls inject_compile_log (line 273) on every response, which reads response['value']['result']['compile_log_id'] (line 332-338) and passes it to download_and_delete_blob. Separately, any response containing 'exception' goes through format_exception (lines 308-325), which reads exception['blobstore_id'] and also calls download_and_delete_blob. That helper (lines 344-349) calls ResourceManager#get_resource(blob_id) and, in an ensure block, ResourceManager#delete_resource(blob_id). ResourceManager (resource_manager.rb:62-70) calls blobstore.delete(id) on the single shared Director blobstore with no UUID-format check, no ownership check, and no namespace prefix.

Affected versions: BOSH Director: All versions prior to v282.1.12

Threat Intelligence Overview

EPSS Score
0.0%
Top 99% exploitable
Data Quality
5 sources
Confidence: Medium

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 MEDIUM
CISA KEV No
Public POC No
EPSS 0.0%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
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· derived
Defer
Exploitation
None
System Exposure· derived
Small
Automatable
No
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

34
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +34
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.

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