CVE-2026-76285

Executive Summary

CVE-2026-76285 is a group identifier assigned by Splunk to a set of internally identified vulnerabilities in Splunk Enterprise that are classified under CWE-710 (Improper Adherence to Coding Standards). The vulnerabilities were addressed across Splunk Enterprise versions 10.4.3, 10.2.7, 10.0.10, and 9.4.15, with one CVE identifier assigned per CWE grouping. Impact is bounded by the individual weaknesses contained in the group; no CVSS score, vector, patch reference, or public exploit code was available in the source intelligence provided for this CVE. Organizations running Splunk Enterprise builds prior to the four fixed releases should treat the exposure as unresolved until they verify their exact build against Splunk's published advisory.

Technical Analysis

The source data for this CVE is deliberately sparse at the technical level, and this analysis is constrained accordingly. What is known with certainty:

• Weakness class: CWE-710, Improper Adherence to Coding Standards. This is a meta-category, not a single defect. It describes code that fails to follow established secure coding practices. Vulnerabilities mapped to CWE-710 inherit whatever the underlying weakness actually is — for example improper input neutralization, missing output encoding, unsafe defaults, or incorrect error handling — because CWE-710 is the parent classification under which those specific defects were grouped.
• Assignment model: Splunk grouped multiple internally discovered vulnerabilities by CWE and assigned one CVE per group. This means CVE-2026-76285 does not map to a single function, module, or code path. It is a bucket identifier covering all internally identified issues in this cycle that were classified under CWE-710.
• Attack surface: Splunk Enterprise is a security information and event management (SIEM) platform. Its exposed surfaces include the web-based management interface, the REST API, the search and indexing pipeline, forwarder communication, and various app/add-on endpoints. The source data does not identify which of these surfaces are implicated.
• No disclosed mechanism: The NVD description does not name a function, class, file path, URL endpoint, or API parameter. The CNA title is empty. No Nuclei template, no exploit code, and no PoC are available. Any statement about a specific injection point, authentication bypass path, or memory-safety condition would be fabrication.

What can be stated at the vulnerability-class level: coding-standard deviations in a platform like Splunk Enterprise most commonly manifest as weak input validation on exposed interfaces, improper handling of untrusted data before it reaches a parser or query engine, or reliance on unsafe defaults. In a SIEM product, such deviations are consequential because the platform ingests untrusted data by design — log events, forwarder payloads, search queries, and app content all cross trust boundaries. A defect in input handling can therefore potentially be triggered by content that the platform is expected to process, not only by a direct attacker request.

Because the grouping is by CWE rather than by component, defenders should not assume the weaknesses are confined to a single subsystem. The relevant defensive posture is to treat every internet- or network-exposed Splunk interface as potentially affected until the vendor advisory is consulted for the per-CWE breakdown that Splunk references ("See Details for more information").

EPSS for this CVE is 0.00139, placing it at the 2.8th percentile of all scored CVEs. This indicates low modeled near-term exploitation likelihood, consistent with the absence of public exploit code, the absence of a CISA KEV entry, and the internal-discovery origin of the flaws.

Exploitation Scenarios

No public PoC is available; the attack chain below is inferred from the vulnerability class (CWE-710) and the affected product category. It does not assert specific implementation details, because none were provided.

1. Reconnaissance and target identification. An adversary enumerates exposed Splunk Enterprise deployments, typically by locating the web management interface, the REST API port, or management endpoints reachable from their position. Shodan-class searches for Splunk products, Splunk HTTP titles, and Splunk TLS certificates identify candidate hosts. The attacker then fingerprints the build to determine whether it predates 10.4.3, 10.2.7, 10.0.10, or 9.4.15.

2. Triggering the flaw class. Because the CVE groups multiple coding-standard deviations under CWE-710, the trigger depends on which underlying weakness the attacker targets. At the class level, the plausible triggers are: supplying malformed or specially structured input to an exposed interface that fails to validate or neutralize it correctly; interacting with an endpoint whose default configuration or error handling is unsafe; or delivering content through a data-ingestion path that the platform processes without sufficient sanitization. The attacker probes these surfaces with boundary-case and malformed inputs and observes anomalous responses, errors, or state changes.

3. Payload and execution method. No payload is described in the source data. The execution outcome is determined by the specific weakness: it could range from information disclosure, to bypass of an intended control, to code or command execution, depending on the actual defect. This report does not claim any of these outcomes as confirmed. Attackers would iterate from the trigger step to whatever primitive the defect yields — reading protected data, altering platform state, or, in the worst case, executing in the context of the Splunk service.

4. Post-exploitation impact. A SIEM platform is a high-value target because it centralizes authentication data, log telemetry, and often credentials or tokens used by integrated systems. Successful exploitation of any defect in this group could expose indexed security data, allow tampering with detection content, or provide a foothold that is trusted by downstream systems. The blast radius extends beyond the Splunk host to everything whose logs, alerts, or integrations flow through it.

Because the individual weaknesses are not enumerated in the source data, this section is intentionally limited to the class-level chain. Defenders should prioritize the vendor advisory's per-CWE detail to build a precise trigger model.

Impact Assessment

• CVSS: No CVSS score or vector was provided. Impact cannot be quantified from the source data. The "N/A" score should not be read as "no impact" — it reflects the absence of a published assessment for this grouped CVE, not a vendor determination of zero severity.
• Affected systems: Splunk Enterprise deployments running builds prior to the four fixed releases (10.4.3, 10.2.7, 10.0.10, 9.4.15). Exact vulnerable ranges were not enumerated in the source data; administrators must map their build against the corresponding maintenance branch.
• Business impact: Splunk Enterprise is frequently positioned as a security-critical control plane. Compromise or manipulation of the platform degrades detection and response capability across the entire monitored estate, and can expose the sensitive telemetry the platform was deployed to protect. Even non-execution outcomes (information disclosure, control bypass) carry elevated business risk because of the data concentration.
• Blast radius: Potentially broad within a given deployment — every forwarder, app, and integrated tool that trusts the Splunk instance is downstream of a successful exploit.
• Exploitation likelihood: Low near-term. EPSS 0.00139 (2.8th percentile), no CISA KEV listing, no public PoC, no Nuclei template, and no exploit code observed.

Detection Guidance

The detection content below targets the vulnerability class and the product, since no specific trigger signature exists. Rules are provided as starting points and should be tuned to the environment to avoid false positives on legitimate administrative activity.

Sigma Rule

title: Suspicious Splunk Enterprise Management and API Requests Indicative of CWE-710 Exploitation Attempts
id: 7c1f9a2e-4b6d-4f3a-9e21-0a5c8d3b6f10
status: experimental
description: Detects anomalous or malformed requests to Splunk Enterprise web and REST interfaces that may indicate probing or exploitation of coding-standard weaknesses grouped under CVE-2026-76285 (CWE-710).
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-76285
author: valtersit.com
date: 2026-01-01
logsource:
  category: webserver
  product: splunk
detection:
  selection_paths:
    - cs-uri-stem|contains:
        - '/services/'
        - '/en-US/'
        - '/api/'
  selection_indicators:
    - cs-uri-query|contains:
        - '../'
        - '%00'
        - '<script'
        - '${'
        - '{{'
  selection_status:
    - sc-status:
        - 400
        - 401
        - 403
        - 500
  condition: selection_paths and selection_indicators and selection_status
falsepositives:
  - Legitimate administrative tooling sending encoded query parameters
  - Automated scanners operated by the security team
level: medium
tags:
  - attack.initial_access
  - attack.t1190
  - cve.2026.76285

YARA Rule

rule CVE_2026_76285_Splunk_CWE710_Probe
{
    meta:
        description = "Detects common exploit-probe payload markers targeting Splunk Enterprise interfaces for coding-standard weaknesses grouped under CVE-2026-76285 (CWE-710). Heuristic only; no confirmed exploit signature exists."
        author = "valtersit.com"
        date = "2026-01-01"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-76285"
        tlp = "WHITE"

    strings:
        $splunk1 = "Splunk" ascii wide nocase
        $splunk2 = "/services/auth" ascii wide nocase
        $probe1  = "../" ascii
        $probe2  = "%00" ascii
        $probe3  = "<script" ascii nocase
        $probe4  = "${" ascii
        $probe5  = "{{" ascii

    condition:
        (uint16(0) == 0x5A4D or uint32(0) == 0x464C457F or true) and
        $splunk1 and
        2 of ($probe*)
}

Suricata IDS Rule

alert http any any -> any any (msg:"CVE-2026-76285 Splunk Enterprise Suspected Coding-Standard Exploitation Probe"; flow:established,to_server; http.method; content:"GET"; http.uri; content:"/services/"; http.uri; content:".."; distance:0; http.header; content:"User-Agent"; pcre:"/(sqlmap|nikto|nuclei|python-requests)/i"; classtype:attempted-recon; sid:202676285; rev:1; metadata:created_at 2026_01_01, cve CVE_2026_76285, affected_product Splunk_Enterprise;)

Elastic Detection

sequence by host.name, user.name with maxspan=5m
  [ network where event.action == "network_flow" and
      network.direction == "inbound" and
      destination.port in (8000, 8089, 8888) and
      url.path : ("/services/*", "/api/*", "/en-US/*") ]
  [ network where event.action == "network_flow" and
      network.direction == "inbound" and
      destination.port in (8000, 8089, 8888) and
      url.query : ("*../*", "*%00*", "*<script*", "*${*") ]

Splunk SPL Query

index=_internal sourcetype=splunkd_web_access OR sourcetype=splunk_web_access
| eval uri = coalesce(uri, url, uri_path)
| where match(uri, "(?i)(\.\./|%00|<script|\$\{|\{\{)")
| stats count min(_time) as first_seen max(_time) as last_seen values(status) as status_codes by clientip, uri, useragent
| where count > 3
| convert ctime(first_seen) ctime(last_seen)
| sort - count

Wazuh OSSEC Rule

<group name="splunk,web,attack,">
  <rule id="202676" level="10">
    <decoded_as>web-accesslog</decoded_as>
    <field name="url">/services/</field>
    <regex type="pcre2">(?i)(\.\./|%00|<script|\$\{|\{\{)</regex>
    <description>CVE-2026-76285: Suspicious request to Splunk Enterprise interface indicating coding-standard weakness probe</description>
    <mitre>
      <id>T1190</id>
    </mitre>
    <group>cve_2026_76285,</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 0/4 (UNPATCHED — no patch evidence from any tracked source). The fixed release identifiers provided by the vendor are listed below, but no patch reference, vendor fix text, or workaround was available in the source data for verification; treat the upgrade path as the primary action and validate against Splunk's official advisory.

1. Immediate mitigations

   • Restrict network access to the Splunk web management interface, REST API port, and management ports to trusted administrative networks only. Do not expose Splunk interfaces directly to the internet.
   • Enforce strong authentication and role-based access control; ensure no default or shared credentials exist on administrative accounts.
   • Enable and review audit logging on all Splunk interfaces to capture malformed or anomalous requests while a permanent fix is validated.
   • Apply virtual patching at the perimeter (WAF/IDS) using the class-level signatures above to flag probing behavior.

2. Patch/upgrade steps

   • Determine the exact installed Splunk Enterprise build and its maintenance branch.
   • Upgrade to the fixed release for the corresponding branch: 10.4.3, 10.2.7, 10.0.10, or 9.4.15.
   • Consult the vendor's advisory "Details" section referenced in the NVD description for the per-CWE breakdown of the grouped vulnerabilities, and verify that all issues in the group are addressed by the target release.
   • Validate the upgrade in a staging environment before production rollout, and confirm that forwarders, apps, and integrations remain functional afterward.

3. Long-term hardening

   • Establish a recurring patch cadence aligned to Splunk's maintenance releases and monitor vendor advisories for future grouped CVE publications.
   • Segment Splunk infrastructure from general-purpose networks; treat the SIEM as a tier-0 asset.
   • Continuously audit custom apps, scripts, and integrations for adherence to secure coding standards, since CWE-710 groups defects of exactly this nature.
   • Maintain detection coverage for anomalous administrative and API activity, and periodically review EPSS/KEV status for this and related CVEs.

References

• NVD — CVE-2026-76285: https://nvd.nist.gov/vuln/detail/CVE-2026-76285
• Splunk Security Advisories (vendor advisory portal): https://advisory.splunk.com/
• CWE-710 — Improper Adherence to Coding Standards: https://cwe.mitre.org/data/definitions/710.html
• MITRE ATT&CK T1190 — Exploit Public-Facing Application: https://attack.mitre.org/techniques/T1190/
• FIRST EPSS — CVE-2026-76285 scoring record: https://api.first.org/data/v1/epss?cve=CVE-2026-76285

Threat actor campaigns and exploit-in-the-wild evidence: none identified. The CVE is not listed in CISA KEV, has no public PoC or exploit code, no Nuclei template, and an EPSS score of 0.00139 (2.8th percentile). No attribution to a named threat actor is supported by the available data.