🔥 CyberForge CVE of the Day #054
🚨 CVE-2026-76460 — Cisco ISE Authentication Bypass
The system deciding who belongs on your network needs its own identity checks to hold. This API boundary does not.
Cisco's published CVE record describes a remote, unauthenticated route into Identity Services Engine through an insufficiently protected API. A crafted request can bypass the web-management authentication boundary without user interaction. Cisco PSIRT confirms active exploitation.
The Cisco CNA's CVSS v3.1 score is 10.0 Critical. CISA added the vulnerability to KEV on 16 September 2026.
⚠️ Treat reachable vulnerable nodes as an urgent patching and compromise-assessment priority.
🎯 The quick hit:
🔹 Affected products: Cisco ISE and ISE-PIC.
🔹 The flaw: an API accepts access that should require authentication.
🔹 The response: inventory every node, constrain reachability, preserve evidence and install the correct branch fix.
🔹 The recovery question: did an intruder alter the system before remediation?
🔑 Key details:
⭐ Severity: Critical
📊 CVSS v3.1: 10.0 — Cisco CNA
🧮 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
🧠 Weakness: CWE-648 — Incorrect Use of Privileged APIs
🎯 Targets: Cisco ISE and ISE Passive Identity Connector
🧩 Vulnerable boundary: Network caller → privileged API access
🌐 Attack vector: Network
⚙️ Attack complexity: Low
🔓 Privileges required: None
👆 User interaction: None
🔀 Scope: Changed
⚔️ Confirmed impact: Authentication bypass and unauthorised device access
💥 CVSS impact: High confidentiality, integrity and availability impact
👤 Execution context: Cisco warns root command execution may follow exploitation
🛡️ Fix: Branch-specific releases listed below
🔑 Additional remediation: Assess compromise; recovery and secret review as appropriate
🚨 Active exploitation: Confirmed by Cisco PSIRT; CISA KEV listed
🧪 Reproduction: No credible CVE-specific public PoC established in our search
📋 CISA KEV: Added 2026-09-16; due 2026-09-19
📉 EPSS: No score returned by FIRST at review time
🗓️ Earliest confirmed attacks: Not dated in the reviewed official evidence
🩹 Vendor patch/hotfix: Fixed matrix published 2026-09-16
📜 Vendor bulletin: cisco-sa-ISE-ABP-VNSW7Tn5
🏷️ Researcher name: None attributed in our reviewed evidence
🔬 Campaign research: No detailed public campaign established in this review
Status checked: 17 September 2026. The published score is v3.1; a v4.0 score is not supplied in the reviewed CNA record.
🧬 What actually went wrong?
A privileged API should verify identity before allowing protected operations, including requests that never pass through the login page.
The CNA describes insufficient authentication control on an API endpoint. The failure gives a remote caller unauthorised access to the device through a crafted request.
1️⃣ Untrusted input arrives
The attacker reaches the affected API without valid credentials.
2️⃣ The authentication boundary fails
The operation accepts a request without enforcing the expected identity check.
3️⃣ Protected access follows
The caller gains access outside the intended management login process.
CWE-648 does not identify the exact coding error. The URI, parameters and implementation remain undisclosed.
⚔️ The practical attack chain:
1️⃣ Reach a vulnerable API from the attacker's network position.
2️⃣ Submit the crafted request described by the CNA.
3️⃣ Bypass the API's authentication control.
4️⃣ Gain unauthorised access to the device.
5️⃣ Investigate what followed; do not assume a specific payload or persistence mechanism.
Steps 2–4 are the disclosed mechanism. Reachability analysis and follow-on investigation are CyberForge guidance. No required companion CVE or weaponised reproduction is established here.
👤 Execution context — what the attacker actually gets.
Cisco's operational warning extends to possible root command execution and concealment of local evidence. The public material does not explain every intermediate step from the bypass to that outcome.
CyberForge interpretation: Investigate appliance integrity, stored secrets, persistence and telemetry trust when assessing recovery.
The wider scope depends on integration permissions, accessible credentials, segmentation and connected services.
Not established: universal domain-administrator access, theft, ransomware, persistence or lateral movement. CVSS scope change does not prove an observed pivot.
📦 Affected products and versions:
Cisco's advisory covers ISE and ISE-PIC regardless of configuration. The CNA enumerates the following affected ISE builds:
🔴 Cisco ISE — explicitly listed affected builds
🔹 3.1: patches 8–11
🔹 3.2: patches 7–10
🔹 3.3: patches 1–11
🔹 3.4: base 3.4.0 and patches 1–6
🔹 3.5: base 3.5.0 and patches 1–3
🔴 Cisco ISE-PIC — explicitly listed affected builds
🔹 Base 3.4.0 and 3.5.0 appear in the CNA record.
Unlisted versions have unknown status in the CNA record. Omission does not certify an older build as safe; use Cisco's fix matrix.
🟢 First fixed releases — ISE / ISE-PIC
🔹 3.1 → 3.1 Patch 12
🔹 3.2 → 3.2 Patch 11
🔹 3.3 → 3.3 Patch 12
🔹 3.4 → 3.4 Patch 7
🔹 3.5 → 3.5 Patch 4
For 3.0, Cisco directs migration to a supported fixed release. Its maintenance footnote mentions 3.0 despite the marker appearing beside the 3.5 row; it does not change the 3.5 fix above.
Inventory advice: Check every node, including standby and disaster-recovery systems. Record role, management address and installed patches.
🕰️ Timeline / exploitation window:
🟢 16 September, 16:00 UTC: Cisco advisory published with the fixed-release matrix.
🔴 16 September: CISA added CVE-2026-76460 to KEV.
🔴 16 September, 20:12 UTC: The official CVE record was published, including Cisco's acknowledgement of active exploitation.
🔎 17 September: CyberForge review; official CVE, vendor and KEV evidence checked. FIRST returned no EPSS row.
📋 19 September: Due date recorded in the KEV entry.
Operational conclusion: Disclosure time is not the start of a proven attack window. Establish how long each node was vulnerable and reachable, then hunt as far back as retained evidence and exposure history justify.
👁️ Defender hunting guide:
Cisco log guidance and CyberForge investigation suggestions follow. No complete campaign IOC set was established.
1️⃣ Establish exposure per node
Record versions, patches, API reachability, ACL history and remediation times. Include VPN, administration-network and jump-host access where present.
2️⃣ Review API access telemetry
Cisco provides this non-exhaustive username check for every node:
show logging application ise-kong/access.log | include dummyuser
Cisco's historical-log route uses a support bundle with debug logs and shared-key encryption. After decryption, the access logs are under:
./ise/logs/apigateway/access.log.<date>.gz
CyberForge advice: Preserve exports before filtering. The username is one lead; its absence cannot exclude variants, expired logs or tampering.
Correlate timestamps, sources and request metadata with administrators, automation and change windows. The log path is not a vulnerable endpoint.
3️⃣ Assess configuration and appliance integrity
Analyst suggestions: Compare configuration with approved changes. Investigate unexplained accounts, policies, logging changes and integrations.
Use supported collection methods or TAC assistance. Investigate unexpected processes, files and persistence where forensic access permits; avoid ad hoc tooling that could alter evidence.
4️⃣ Correlate independent network evidence
Cisco recommends off-device network and firewall review. CyberForge extension: Use flow, DNS and proxy records where available to investigate unusual destinations or transfers around suspicious API activity.
Distinguish approved updates, backups and monitoring from unexplained connections. Correlate source node, destination, time and transfer volume with the API evidence.
5️⃣ Review identities and connected secrets
Analyst suggestions: Map credentials and keys that the node could access, then examine their use in connected systems. Check for unexpected account changes, new administration sources and activity continuing after remediation.
🩹 Emergency remediation order:
1️⃣ Preserve evidence while containing exposure
Capture logs and configuration history with incident responders while containing malicious access. Record defender changes for the investigation timeline.
2️⃣ Deploy the appropriate supported fix
Use official Cisco software and the branch matrix above. Confirm prerequisites, compatibility and deployment order; track completion per node.
3️⃣ Verify the running state
Confirm each node's installed release, patch level, service health and access controls after maintenance. A downloaded patch is not a verified fix.
4️⃣ Recover suspected compromised nodes
Cisco recommends re-imaging affected nodes when malicious activity is suspected, restoring configuration if needed. CyberForge extension: assess backup trust and review what will be restored; otherwise unauthorised settings could return with an apparently successful recovery.
5️⃣ Review and replace exposed secrets
This is an analyst recommendation based on access and findings, not a blanket vendor claim that every key was stolen. Coordinate revocation or rotation from a trusted administration path with containment and recovery. Avoid introducing replacement secrets into a still-untrusted node; preserve essential service dependencies.
6️⃣ Validate recovery and continue monitoring
Reconcile configuration with the approved baseline, check integrations and monitor further activity. Document unresolved evidence gaps and residual risk.
🧱 Temporary exposure reduction.
Cisco offers no workaround that fixes the flaw. Infrastructure ACLs can temporarily restrict incoming traffic to required management and control-plane flows.
CyberForge implementation checks:
✅ Identify required flows before changing rules so authentication services remain available.
✅ Apply restrictions to every relevant node and address, including alternate management paths.
✅ Review broad VPN or “trusted network” allowances that grant unnecessary reachability.
✅ Confirm the effective access policy using approved methods and existing telemetry.
✅ Time-limit exceptions and assign an owner to remove them.
🚑 When vulnerability management becomes incident response.
Escalate for investigation when API anomalies, unauthorised configuration changes or unexplained network activity suggest access beyond routine administration.
🔴 Unexplained privileged-account or policy changes
🔴 Correlated API and outbound-traffic anomalies
🔴 Evidence of persistence or altered logging
🔴 Connected credentials behaving abnormally after patching
These are investigation criteria, not observed campaign behaviours. Coordinate isolation, evidence preservation and credential response. Exposure alone proves neither exfiltration nor ransomware.
📊 CISA KEV and EPSS context.
At review on 17 September:
🔹 KEV includes this CVE, added 16 September, due 19 September.
🔹 The retrieved catalogue flags forensic triage Yes and ransomware use Unknown.
🔹 FIRST returned no EPSS record. That means unavailable, not zero probability.
The CNA record also carries CISA's SSVC assessment: exploitation active, automatable yes, technical impact total.
Direct exploitation evidence already establishes urgency. A missing forecast provides no reason to wait. The catalogue due date is an action date in that programme, not a safe period for other organisations to remain exposed.
🧾 Evidence separation.
Vendor-confirmed: API authentication bypass, affected product scope, published fixes and active exploitation. Cisco also provides detection and recovery guidance and warns of possible root-level consequences.
Researcher-reported / reproduced: No independently validated CVE-specific public reproduction was established in this review. A generic exploit-collection search result does not prove one exists.
CyberForge interpretation: Prioritise reachable identity infrastructure, investigate every node, correlate independent telemetry and assess secrets according to the access actually obtained.
Not established: exact vulnerable URI or parameter, implementation-level patch details, mandatory companion CVE, earliest attack date, actor attribution, victim count or a complete IOC set. Independent NVD content could not be retrieved during the report research; scoring here is Cisco CNA scoring.
🔥 CyberForge verdict:
CVE-2026-76460 is an actively exploited break in a sensitive authentication boundary. The operational challenge is to close the exposure while determining whether the system's configuration and connected trust relationships remain sound.
The correct order is:
1️⃣ Contain reachability and preserve available evidence.
2️⃣ Install the appropriate fix and verify every node.
3️⃣ Hunt the actual exposure period.
4️⃣ Recover suspected compromised nodes through the vendor-supported path.
5️⃣ Revoke or rotate exposed secrets in coordination with recovery.
6️⃣ Monitor connected systems for continued abuse.
Repair the trust boundary, then establish whether anyone crossed it before the repair.
🔗 Cisco advisory, fixes and recovery guidance:
https://www.cisco.com/c/en/us/support/docs/csa/cisco-sa-ISE-ABP-VNSW7Tn5.html
🔗 Official CVE record — Cisco CNA / CISA ADP:
https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/76xxx/CVE-2026-76460.json
🔗 CISA KEV:
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-76460
🔗 FIRST EPSS:
https://api.first.org/data/v1/epss?cve=CVE-2026-76460
🔗 NVD record — reference link:
https://nvd.nist.gov/vuln/detail/CVE-2026-76460
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