CVE-2026-76488

Executive Summary

CVE-2026-76488 is an insufficient access control vulnerability in the export policies functionality of Cisco Application Policy Infrastructure Controller (APIC) that allows an authenticated remote attacker holding valid administrative credentials to read sensitive files from the underlying file system, including key material. The flaw carries a CVSS 3.1 base score of 6.5 (AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N), reflecting high confidentiality and integrity impact gated behind administrative privileges. A successful exploit can expose cryptographic key material usable to elevate privileges to root on the affected APIC and on managed switches, meaning the blast radius extends beyond the controller into the fabric it governs.

Technical Analysis

The reported root cause is insufficient access control to file system resources within the export policies feature of Cisco APIC. In operation, export policies in APIC-driven environments are administrative constructs that define how configuration and operational data are exported — the UI surfaces associated with them accept operator-supplied values that determine what is rendered or exported. The vulnerability arises because those inputs are not adequately validated or constrained relative to the underlying file system, allowing a path-style value supplied through specific UI fields to resolve outside the intended export scope.

The attack surface is the authenticated administrative web UI. Exploitation is not anonymous: the CVSS vector (PR:H) and the description both require valid administrative credentials, and both the access vector (AV:N) and the absence of a user-interaction requirement (UI:N) indicate a remotely reachable, scriptable trigger that does not depend on a victim clicking anything. The relevant weakness class is CWE-264 (Permissions, Privileges, and Access Controls), which is consistent with a missing authorization or missing path-constraint check on a resource-facing operation rather than a memory-safety defect.

The NVD description does not disclose the specific field names, endpoint paths, file paths, parameter names, or code functions involved. No public advisory, commit, or patch diff has been tracked, so no code-level detail beyond the description can be asserted. What can be stated with confidence from the description alone is: (a) the flaw is a server-side access control failure in a file-export code path, (b) it is exercised through user-supplied values in named UI fields, and (c) the resulting read capability reaches sensitive files including key material. The precise mechanism by which the crafted value escapes its intended scope (for example, a traversal-style path or a missing allowlist check) is not specified in the available data and should not be assumed.

Critically, the confidentiality impact is assessed as High and the integrity impact is also High. Integrity impact in an information-disclosure-only bug is notable: it follows from the described second-order effect, in which recovered key materials enable privilege escalation to root on the APIC and on managed switches. That converts a read primitive into a platform-compromise primitive.

Exploitation Scenarios

No public proof-of-concept, exploit code, or Nuclei template exists for CVE-2026-76488 as of the tracking data. The attack chain below is therefore described at the vulnerability-class level, inferred strictly from the NVD description. No specific function names, endpoint paths, file paths, or parameter identifiers are asserted because none are provided in the source data.

1. Reconnaissance and target identification. The attacker identifies a reachable Cisco APIC management interface. Because exploitability requires administrative credentials, this stage is primarily about obtaining or already possessing privileged access — the vulnerability is an insider-adjacent or post-credential-compromise primitive. A Shodan-style query such as http.title:"Cisco APIC" or ssl.cert.subject.cn:"Cisco APIC" supports identification of exposed controllers on the public internet. Reconnaissance therefore targets both the exposure of the UI and the credential path by which administrative access is obtained.

2. Triggering the flaw class. With an authenticated administrative session, the attacker interacts with the export policies functionality through the UI. The attacker submits crafted values into the specific UI fields that the export policy configuration accepts, rather than well-formed export parameters. The insufficient access control on file system resources means the submitted value is not constrained to the intended export scope, and the server-side handling resolves it against the underlying file system. This is an access-control failure: the request is authorized at the session level but not at the resource level, so a legitimate administrative account reaches files it is not intended to reach.

3. Payload and execution method. At the vulnerability-class level, this is path/resource-scope manipulation delivered as field input — an attacker-controlled value passed to a file-handling operation that lacks a constraint check. The payload is carried in normal UI field submissions over the authenticated session; no memory corruption, deserialization gadgetry, or client-side execution is indicated by the description. Because UI:N, an automated script replaying authenticated requests can exercise the flaw repeatedly and selectively.

4. Post-exploitation impact. A successful exploit returns contents of sensitive files from the device's underlying file system. Per NVD, this includes key materials. Those key materials can be leveraged to elevate privileges to root on the affected APIC and, critically, on managed switches. Root on the controller is a fabric-wide event: APIC manages the switches, so key material and privilege obtained at the controller tier can propagate to the managed network devices. The end state is not confidentiality loss alone but a credible path to full control of the software-defined networking estate.

Impact Assessment

The CVSS 3.1 base score is 6.5 with vector AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N. Findings per subscore:

• Attack Vector (Network): the management UI is reachable over the network; exposed APIC interfaces materially raise risk.
• Attack Complexity (Low): no special preconditions beyond valid credentials are indicated; the crafted value is submitted through ordinary UI interaction.
• Privileges Required (High): the single largest mitigating factor. An attacker must already hold valid administrative credentials. This prevents the flaw from being an unauthenticated pre-auth target and is the reason the base score sits in the medium range despite High/High confidentiality and integrity impact.
• User Interaction (None): no victim action is needed once credentials exist, making scripted exploitation straightforward.
• Scope (Unchanged): the vulnerable component is assessed as impacted within its own security authority, though the described downstream effect on managed switches is significant operationally.
• Confidentiality (High): sensitive files, including key materials, are disclosed.
• Integrity (High): the key-material disclosure enables privilege escalation to root on the APIC and managed switches, an integrity and control outcome rather than a read-only one.
• Availability (None): no denial-of-service condition is described.

Business impact centers on the SDN control plane. APIC is the management controller for Cisco ACI fabrics; compromise of APIC is effectively compromise of the network policy foundation. Because key material from the controller can be used to escalate to root on managed switches, a single administrative foothold on APIC can chain into fabric-wide root access. Blast radius is therefore "all devices under APIC management," not just the controller itself. The EPSS score is 0.00285 (19.3rd percentile), indicating low modeled near-term exploitation probability, and the CVE is not in CISA KEV. That said, low EPSS here is heavily influenced by the PR:H requirement; it should not be read as "not worth patching," because the qualifying credential set is exactly the set that already has the most access in an ACI environment.

Detection Guidance

Sigma Rule

title: Cisco APIC Export Policies Sensitive File Access Attempt (CVE-2026-76488)
id: 8f2c1a90-4b7e-4c3a-9d21-0a6e5f764880
status: experimental
description: Detects suspicious requests against Cisco APIC export policy UI fields that may indicate exploitation of insufficient access control (CVE-2026-76488). Requires administrative session context.
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-76488
author: valtersit.com
logsource:
  product: cisco
  service: apic
  category: webserver
detection:
  selection_path:
    cs-uri-stem|contains:
      - '/exportpolicy'
      - '/exportPolicies'
      - '/exportPolicy'
  selection_indicators:
    cs-uri-query|contains:
      - '..'
      - '%2e%2e'
      - '/etc/'
      - 'file://'
      - '/root/'
  condition: selection_path and selection_indicators
fields:
  - c-ip
  - cs-username
  - cs-uri-stem
  - cs-uri-query
  - sc-status
falsepositives:
  - Legitimate export policy administration referencing relative paths
level: high
tags:
  - attack.t1190
  - cve.2026-76488

YARA Rule

rule CVE_2026_76488_APIC_ExportPolicy_Traversal
{
    meta:
        description = "Detects exploitation attempts of Cisco APIC export policies access control flaw (CVE-2026-76488) in HTTP request logs or proxy captures"
        author = "valtersit.com"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-76488"
        date = "2026-01-01"
        severity = "high"

    strings:
        $export = "export" nocase
        $policy = "policy" nocase
        $trav1 = "../" ascii
        $trav2 = "..%2f" ascii nocase
        $trav3 = "%2e%2e%2f" ascii nocase
        $key1 = "/etc/shadow" ascii
        $key2 = "/root/" ascii
        $apic = "APIC" ascii

    condition:
        uint16(0) == 0x4854 and
        $apic and
        $export and
        $policy and
        any of ($trav*) or any of ($key*)
}

Suricata IDS Rule

alert http any any -> any any (msg:"CVE-2026-76488 Cisco APIC Export Policies Access Control Bypass Attempt"; flow:established,to_server; http.method; content:"POST"; http.uri; content:"export"; nocase; http.uri; content:"policy"; nocase; http.request_body; content:"../"; http.request_body; content:"..%2f"; nocase; threshold:type limit, track by_src, count 5, seconds 60; reference:cve,2026-76488; reference:url,nvd.nist.gov/vuln/detail/CVE-2026-76488; classtype:attempted-admin; sid:202676488; rev:1;)

Elastic Detection

sequence by user.name, source.ip with maxspan=5m
  [http where http.request.method == "POST" and
     stringContains(url.path, "export", false) and
     stringContains(url.path, "policy", false)]
  [http where http.request.method == "POST" and
     (stringContains(url.query, "..", false) or
      stringContains(url.query, "%2e%2e", false) or
      stringContains(url.query, "/etc/", false))]

Splunk SPL Query

index=web sourcetype=cisco:apic OR sourcetype=access_combined
| eval uri=lower(coalesce(uri, cs_uri_stem, url))
| eval query=lower(coalesce(uri_query, cs_uri_query, url))
| where (like(uri, "%export%") AND like(uri, "%policy%"))
| where (like(query, "%..%") OR like(query, "%2e%2e%") OR like(query, "%/etc/%") OR like(query, "%file://%"))
| stats count min(_time) as first_seen max(_time) as last_seen values(query) as queries by src_ip, user
| where count >= 3
| convert ctime(first_seen) ctime(last_seen)
| sort - count

Wazuh OSSEC Rule

<group name="cisco,apic,web,cve-2026-76488,">
  <rule id="764880" level="10">
    <decoded_as>web-accesslog</decoded_as>
    <field name="url">export</field>
    <field name="url">policy</field>
    <regex type="pcre2">(?i)(\.\.|%2e%2e|/etc/|file://)</regex>
    <description>CVE-2026-76488: Possible Cisco APIC export policy access control bypass attempt</description>
    <mitre>
      <id>T1190</id>
    </mitre>
    <group>attack.attempted_admin,</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence is 0/4 (UNPATCHED). No patch, vendor advisory, fixed version, workaround, or affected-version boundary is available from any tracked source. All guidance below is defensive and compensating until Cisco publishes a fixed release.

1. Immediate mitigations:

• Enforce strict network segmentation so the APIC management UI is not reachable from untrusted networks. Restrict access to dedicated out-of-band management networks and administrative jump hosts.
• Audit administrative accounts on all APIC controllers and remove or disable unused and shared admin credentials. Because exploitation requires valid admin rights, credential hygiene directly reduces the exploitable population.
• Apply least privilege: where role-based access supports it, restrict who holds full administrative rights on APIC.
• Increase monitoring of export policy configuration changes and file-export activity, prioritizing authenticated sessions that touch export fields with anomalous values.
• Treat any suspected successful exploitation as a key-compromise event: assume exposure of cryptographic key material and plan for credential and key rotation on the APIC and on managed switches, not just the controller.

2. Patch/upgrade steps:

• Monitor Cisco's security advisory portal and the Cisco ACI/APIC release notes for a fixed software version addressing CVE-2026-76488. No fixed version is known at this time.
• Maintain an inventory of APIC controllers and their firmware versions so that a fixed release, once published, can be deployed promptly and centrally.
• When a fix becomes available, prioritize controllers exposed to less-trusted networks and any controllers where administrative access is broadly shared.

3. Long-term hardening:

• Adopt an SDN-controller-specific threat model: treat APIC as a tier-0 asset whose compromise implies fabric-wide switch compromise.
• Implement controlled key management and periodic rotation of fabric key material so that a single disclosure event cannot be leveraged indefinitely for root-level escalation.
• Harden export and data-handling features by constraining inputs to allowlisted values, and validate on the server side that file paths and exported resources resolve within intended scopes — the general remedy for this class of insufficient access control.
• Continuously monitor for Cisco advisories and integrate CVE feeds for ACI/APIC components into vulnerability management workflows, since the initial tracking data for this CVE carried no fixed-version or workaround information.

References

1. NVD — CVE-2026-76488: https://nvd.nist.gov/vuln/detail/CVE-2026-76488
2. Cisco Security Advisories and Notices (vendor advisory portal — check for an APIC advisory referencing this CVE): https://sec.cloudapps.cisco.com/security/center/publicationListing.x
3. CWE-264 — Permissions, Privileges, and Access Controls: https://cwe.mitre.org/data/definitions/264.html
4. MITRE ATT&CK — T1190 Exploit Public-Facing Application: https://attack.mitre.org/techniques/T1190/
5. FIRST EPSS — CVE-2026-76488 score page (0.00285, 19.3rd percentile): https://api.first.org/data/v1/epss?cve=CVE-2026-76488

Threat-actor and in-the-wild evidence: none. CVE-2026-76488 is not listed in CISA KEV, no public proof-of-concept or exploit code is available, and no tracked campaign is associated with this identifier. Exploitation in the wild has not been confirmed as of the tracking data provided.