CVE-2026-76467

Executive Summary

CVE-2026-76467 is a vulnerability class assigned by Cisco as part of a broader internal security review and software hardening release. It covers issues categorized under CWE-664, "Improper Control of a Resource Through its Lifetime" — a pillar-level weakness describing defects in how a resource is acquired, used, and released. The CVSS v3.1 base score of 7.5 (High) reflects a network-reachable, low-complexity, unauthenticated condition with a high availability impact and no confidentiality or integrity impact, indicating a denial-of-service–oriented issue against affected Cisco products. Because the advisory deliberately aggregates multiple internally discovered vulnerabilities under a single CVE, the exact product, protocol, and affected versions are not disclosed in the available intelligence.

Technical Analysis

CWE-664 is a pillar weakness, not a leaf-level vulnerability. Per the MITRE taxonomy, pillar weaknesses sit at the top of a hierarchy and describe an abstract theme that is expressed in practice through more specific child weaknesses. The CNA description states explicitly that the vulnerabilities tracked by CVE-2026-76467 "are related to issues concerning improper control of a resource through its lifetime." That places this CVE in the family of resource-management defects: the affected software fails to correctly manage the full lifecycle of a resource — acquisition, initialization, use, and release.

Common child weaknesses beneath CWE-664 that manifest as resource-lifecycle failures include:

• CWE-400 — Uncontrolled Resource Consumption: the software does not properly limit the allocation or consumption of a resource, allowing an attacker to exhaust a finite pool (memory, file descriptors, sockets, session slots, queue entries) and deny service to legitimate users.
• CWE-404 — Improper Resource Shutdown or Release: a resource is not released after its useful lifetime, leading to progressive exhaustion over repeated invocations.
• CWE-772 — Missing Release of Resource after Effective Lifetime: memory, handles, or buffers are never freed, producing a steady-state leak that accumulates across requests.
• CWE-410 / CWE-770 — Insufficient Resource Pool / Allocation of Resources Without Limits or Throttling: no ceiling is enforced on concurrent or repeated resource use.

The CVSS vector provides strong, description-consistent evidence for which mechanism class is at play. C:N/I:N/A:H — no confidentiality impact, no integrity impact, high availability impact — is the canonical signature of a resource-exhaustion or resource-release defect. An attacker does not read data and does not alter data; they consume or corrupt the availability of a service. AV:N/AC:L/PR:N/UI:N — network vector, low attack complexity, no privileges, no user interaction — means the flaw is reachable directly over the network by an unauthenticated party, that no special conditions must be engineered at attack time, and that no victim must be socially induced to act. The combination AC:L/UI:N frequently corresponds to a class of trigger that can be driven by a single crafted request or by a modest, repeatable request pattern: for example, a malformed protocol input that causes a resource handle to be retained rather than released, or a request pattern that allocates a resource without an enforced bound.

The natural attack surface for a CWE-664 class defect reachable over the network in a networking vendor's product line is the set of externally exposed management and control planes — for example, device management interfaces, protocol handlers, web-based administration services, or authentication endpoints — where a remote request causes the software to acquire a resource (a session object, a buffer, a socket, a worker slot) whose lifetime is not correctly controlled. Because the CNA has aggregated multiple findings under one CVE and disclosed no per-vulnerability breakout, the specific component, protocol, and resource type cannot be identified from the available data. No function names, endpoints, parameters, or file paths are disclosed in the NVD description or CNA title, and none are asserted here.

Exploitation Scenarios

No public PoC, exploit code, or Nuclei template exists for this CVE, and no technical breakout of the aggregated findings has been published. The following attack chain is therefore described strictly at the vulnerability-class level, consistent with CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. No specific implementation details are inferred or fabricated.

Step 1 — Reconnaissance and target identification. An adversary performs network reconnaissance to identify internet- or intranet-exposed Cisco devices and services. Because the vulnerability is network-reachable with no authentication requirement, targets are the externally visible endpoints of affected products. Enumerating fingerprintable management and service surfaces narrows the target set to devices with reachable, unauthenticated request paths.

Step 2 — Triggering the resource-lifecycle defect. The attacker sends engineered input to the affected network-facing interface. The flaw class indicates that the software improperly controls a resource through its lifetime — either by consuming a resource without an enforced bound, or by failing to release a resource after its effective lifetime. The AC:L/UI:N vector members indicate the trigger does not require complex preconditions or victim cooperation; the PR:N member indicates no valid credentials are needed. In the generic case, a single crafted request or a repeatable request sequence is sufficient to begin depleting or corrupting the resource pool.

Step 3 — Payload/execution method at the vulnerability-class level. No payload syntax, protocol frame format, or request body is published. At the class level, the "payload" is an input that induces the improper allocation, retention, or non-release of a resource. Where the child weakness is uncontrolled consumption (CWE-400/770), the attacker repeats or scales the request until the finite resource is exhausted. Where the child weakness is improper release (CWE-404/772), the attacker issues requests that each leak or strand a resource, so that availability degrades cumulatively over many invocations rather than in a single event.

Step 4 — Post-exploitation impact. The result, consistent with the A:H metric, is degradation to full loss of availability of the affected service or device function. Confidentiality and integrity are not impacted (C:N/I:N), so the objective is denial of service — rendering the device or its service unavailable to legitimate users. Depending on the product and component (undisclosed here), this could affect a single management service, a specific protocol handler, or broader device reachability. There is no evidence of lateral movement, credential theft, or data exfiltration associated with this CVE.

Impact Assessment

The CVSS v3.1 base score is 7.5 (High) with vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

• Attack Vector (AV:N): The flaw is exploitable remotely over a network. This materially increases blast radius because exploitation does not require physical or adjacent access.
• Attack Complexity (AC:L): No special conditions or reconnaissance-dependent preconditions are required at attack time. This lowers the skill floor and increases the likelihood of automated mass exploitation if a trigger becomes public.
• Privileges Required (PR:N): No authentication is needed — unauthenticated parties can attempt exploitation.
• User Interaction (UI:N): No victim must open a file or click a link; the attack is fully automated and server-side triggered.
• Scope (S:U): Impact is confined to the vulnerable component's security authority.
• Confidentiality (C:N) / Integrity (I:N): No data disclosure or data modification expected.
• Availability (A:H): The dominant impact — total loss of availability of the affected resource or service.

Business impact. For enterprises running the affected Cisco products, the operational risk is service interruption. Cisco networking equipment frequently sits on the critical path of network connectivity, remote-access, or management functions; loss of availability in such a component can translate into localized or broader network outages, disrupted remote operations, and management-plane unavailability during incident response. Because exploitation requires no credentials, a moderately capable adversary — or an opportunist with a known trigger — can mount denial-of-service attempts against exposed devices.

Blast radius. Constrained by availability-only impact, but amplified by the network vector and the possibility that affected devices are internet-facing. Absent a disclosed affected-product list, the blast radius cannot be scoped to specific models or firmware trains. Enterprise exposure is highest wherever affected Cisco management or service interfaces are reachable from untrusted networks.

There is no evidence in the provided data of exploitation in the wild, CISA KEV listing, or public PoC. EPSS has not been scored by FIRST.org for this CVE at the time of writing; no EPSS value is asserted.

Detection Guidance

Detection strategy for a CWE-664 resource-lifecycle defect centers on identifying anomalous request volume, resource-consumption patterns, and service-availability degradation against affected Cisco network-facing endpoints. Because no CVE-specific request syntax is published, the following rules target the behavioral signature of resource-exhaustion and non-release exploitation against exposed Cisco services.

Sigma Rule

title: Potential CWE-664 Resource Exhaustion Exploitation Attempt Against Cisco Service
id: 3f8c1a2e-9b47-4d6e-8a21-cisco-cve-2026-76467
status: experimental
description: Detects patterns consistent with unauthenticated resource-lifecycle
  abuse (CWE-664) against Cisco network-facing services, per CVE-2026-76467.
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-76467
author: valtersit.com Threat Intelligence
date: 2026/01/01
tags:
  - attack.t1190
  - cve.2026-76467
logsource:
  category: webserver
  product: cisco
detection:
  selection_status:
    sc-status:
      - 500
      - 502
      - 503
      - 504
  selection_volume:
    |-
    # High-frequency requests from a single source to management/service endpoints
    c-ip: '*'
  timeframe: 1m
  condition: selection_status
falsepositives:
  - Legitimate heavy management traffic
  - Load balancer health-check failures
level: medium

YARA Rule

rule CVE_2026_76467_Cisco_Resource_Lifecycle_Abuse
{
    meta:
        description = "Detects artifacts associated with CWE-664 resource-lifecycle exploitation attempts against Cisco services (CVE-2026-76467)"
        author = "valtersit.com Threat Intelligence"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-76467"
        date = "2026-01-01"
        severity = "high"

    strings:
        $cve  = "CVE-2026-76467" ascii nocase
        $cwe  = "CWE-664" ascii nocase
        $res1 = "resource" ascii nocase
        $res2 = "exhaust" ascii nocase

    condition:
        $cve or $cwe or (2 of ($res*))
}

Suricata IDS Rule

alert http any any -> any any (msg:"CVE-2026-76467 Possible Cisco CWE-664 Resource-Exhaustion DoS Attempt"; flow:established,to_server; http.method; content:"GET"; http.header; content:"Cisco"; nocase; threshold:type both, track by_src, count 100, seconds 60; classtype:attempted-dos; reference:cve,2026-76467; reference:url,nvd.nist.gov/vuln/detail/CVE-2026-76467; sid:202676467; rev:1;)

Elastic Detection

sequence by source.ip with maxspan=1m
  [network where network.protocol == "http" and http.response.status_code >= 500 and
   destination.ip != null]
  [network where network.protocol == "http" and http.response.status_code >= 500 and
   destination.ip != null]

Splunk SPL Query

index=network sourcetype=cisco:* OR sourcetype=suricata
| search (status>=500 OR "resource" OR "exhausted")
| stats count AS attempts, dc(dest_ip) AS targets BY src_ip
| where attempts > 100 AND targets >= 1
| sort - attempts

Wazuh OSSEC Rule

<group name="cisco,cve-2026-76467,">
  <rule id="100764" level="10">
    <decoded_as>json</decoded_as>
    <field name="cve">CVE-2026-76467</field>
    <description>Potential exploitation attempt against Cisco CWE-664 resource-lifecycle vulnerability (CVE-2026-76467)</description>
    <mitre>
      <id>T1190</id>
    </mitre>
  </rule>
  <rule id="100765" level="8">
    <if_sid>100764</if_sid>
    <field name="status">503|504|500</field>
    <description>CVE-2026-76467 - Cisco service degraded following suspected resource exhaustion</description>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 0/4 — UNPATCHED. No patch evidence from any tracked source. The CNA text references a "software hardening release," but no advisory ID, version identifier, download location, or fixed-version mapping was provided in the available data. Until Cisco publishes a per-CVE advisory with affected and fixed versions, treat all potentially affected deployments as unpatched.

1) Immediate mitigations.

• Restrict network exposure of Cisco management and service interfaces to trusted administrative networks; do not expose management planes to the internet or to untrusted segments.
• Apply access-control lists (ACLs), firewall rules, and management-plane hardening to limit which sources can reach device services.
• Enforce rate limiting and request throttling at the network edge to blunt high-volume, unauthenticated resource-exhaustion attempts.
• Enable logging and continuous availability monitoring on Cisco devices to detect degrading service before full denial of service.

2) Patch/upgrade steps.

• Monitor Cisco's official security advisories page for the CVE-2026-76467 advisory. Cisco typically publishes per-vulnerability or bundled advisories with affected product lists and fixed software versions.
• When the advisory is available, identify affected product families and firmware trains, then upgrade to the fixed release through Cisco's standard software-update process.
• Where the hardening release is published as an aggregate advisory, review the full affected-versions table — the CVE groups multiple findings, so a single upgrade may address several enumerated weaknesses.
• Verify update authenticity through Cisco's signed distribution channels.

3) Long-term hardening.

• Segment and minimize the network-exposed attack surface of all Cisco devices; adopt zero-trust principles for management-plane access.
• Deploy resource-consumption monitoring and alerting (memory, sessions, file descriptors, connection tables) so that slow leaks and consumption anomalies are visible.
• Maintain a vulnerability management program that tracks CWE-pillar categories (e.g., CWE-664, CWE-400, CWE-772) across the Cisco fleet, not just individual CVEs.
• Integrate device firmware inventory with advisory-tracking tooling to shorten time-to-patch once fixed versions are published.
• Conduct periodic configuration hardening reviews against Cisco's published hardening guides.

References

1. National Vulnerability Database — CVE-2026-76467: https://nvd.nist.gov/vuln/detail/CVE-2026-76467
2. CWE-664 — Improper Control of a Resource Through its Lifetime (MITRE): https://cwe.mitre.org/data/definitions/664.html
3. Cisco Security Advisories (vendor advisory home; per-CVE advisory pending): https://sec.cloudapps.cisco.com/security/center/publicationListing.x
4. FIRST.org EPSS (not yet scored for this CVE at time of writing): https://www.first.org/epss/
5. CISA Known Exploited Vulnerabilities Catalog — no listing for CVE-2026-76467: https://www.cisa.gov/known-exploited-vulnerabilities-catalog

No public proof-of-concept, exploit code, Nuclei template, registered forensic artifact hash, exploit-in-the-wild evidence, or named threat-actor campaign exists for CVE-2026-76467 in the available data. CISA KEV status: NO. The CVE is not yet scored by FIRST.org for EPSS.