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Splunk Enterprise CVE-2026-76271

| EUVDEUVD-2026-94623 MEDIUM
Inefficient Algorithmic Complexity (CWE-407)
2026-10-07 cisco GHSA-pf4p-427j-r97p
6.5
CVSS 3.1 · Vendor: cisco
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Attack ChainAIDerived

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

  1. Access
    Authenticate as low-privileged Splunk user
  2. Delivery
    Reach Observability Cloud app REST endpoint
  3. Exploit
    Submit crafted input triggering inefficient regex
  4. Execution
    Catastrophic backtracking exhausts CPU
  5. Impact
    Denial of service for REST API

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V2 - Validation and Business Logic Algorithmic complexity limits
Exploitation Conditions

Requires an authenticated Splunk account that does NOT need the 'admin' or 'power' roles - any low-privileged user suffices (PR:L). The specific vulnerable surface is the REST API endpoint of the 'Discover Splunk Observability Cloud app', which the vendor documents as a preview feature; exploitation presupposes this app/endpoint is present and reachable, so environments without the Observability Cloud preview enabled are not exposed. Exploitation is limited to affected 10.x branches (10.4.x below 10.4.3, 10.2.x below 10.2.7, 10.0.x below 10.0.10); version 9.4.x is explicitly not affected. No user interaction is required (UI:N) and impact is confined to availability (DoS via inefficient-regex CPU exhaustion), with no data exposure or modification.

Impact

This is a moderate-priority, availability-only vulnerability rather than a top-tier emergency. The CVSS 3.1 vector (AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H) correctly scores it 6.5 MEDIUM: network-reachable with low attack complexity, but it requires an authenticated low-privileged account (PR:L) and yields only a denial of service (A:H) with no confidentiality or integrity impact. The root cause is CWE-407 (algorithmic complexity / inefficient regular expression, i.e. a ReDoS) in input validation for a REST API endpoint, so a crafted input can pin CPU and starve the service. No EPSS score was provided in the input, the CVE is NOT listed in CISA KEV, and no public exploit was supplied - so there is no public exploit identified at time of analysis and no evidence of active exploitation. The signals are internally consistent (authenticated, DoS-only), with no CVSS-vs-description conflict. The main caveat is exposure scope: the flaw lives in the 'Discover Splunk Observability Cloud app', described as a preview feature, so real-world impact depends on whether that app/endpoint is actually enabled, which likely narrows exposure well below the full Splunk Enterprise install base.

Exploit ScenarioDerived

An attacker who already holds a basic, non-admin/non-power Splunk account (or who compromises such low-privileged credentials) sends a specially crafted input to the REST API endpoint exposed by the Discover Splunk Observability Cloud app. Because the endpoint validates input with an inefficient regular expression, the request triggers catastrophic backtracking that consumes CPU and degrades or halts the service for other users. No public proof-of-concept was provided, and exploitation is remote (AV:N) with low complexity but requires valid authentication.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.3% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 07, 2026

Denial of service in Splunk Enterprise 10.x allows an authenticated user with only low-privileged roles to degrade or take down a REST API endpoint exposed by the Discover Splunk Observability Cloud app, because the app validates input with an inefficient regular expression that can be driven into excessive CPU consumption. Affected branches are 10.4.x below 10.4.3, 10.2.x below 10.2.7, and 10.0.x below 10.0.10; Splunk Enterprise 9.4.x is explicitly not affected, and the exposure only exists where the Observability Cloud preview app and its endpoint are present and reachable. Impact is confined to availability (no data disclosure or modification), no public exploit code has been identified at time of analysis, and the vendor has released fixes in 10.4.3, 10.2.7, and 10.0.10.

RemediationAI

Vendor-released patch: upgrade Splunk Enterprise to 10.4.3, 10.2.7, or 10.0.10 according to your release train, as documented in the Splunk advisory SVD-2026-1001 (https://advisory.splunk.com/advisories/SVD-2026-1001). Until upgrading is possible, the most direct compensating control is to remove the attack surface: disable or uninstall the Discover Splunk Observability Cloud app preview, or otherwise restrict its REST endpoint from ordinary authenticated users via role-based access configuration; the trade-off is loss of the observability preview functionality for those users. If the feature must stay available, restrict the endpoint to a small set of trusted accounts using Splunk's role and capability configuration (the vulnerable path only requires the low privileges available to non-admin, non-power users, so narrowing who can reach it materially reduces exposure), and apply network or reverse-proxy filtering so the endpoint is not reachable from untrusted networks. Because exploitation manifests as CPU exhaustion, additionally monitor for abnormal CPU spikes and repeated requests to the Observability Cloud REST endpoints as a detection control rather than a prevention control. Note that 9.4.x installations require no action for this specific issue.

Affected VersionsENISA

Splunk Enterprise 10.4 <10.4.3
Splunk Enterprise 10.2 <10.2.7
Splunk Enterprise 10.0 <10.0.10

Affected Packages

euvd splunk_enterprise fix: 10.0.10, 10.2.7, 10.4.3

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

The root cause is CWE-407 (Inefficient Regular Expression Complexity): the Discover Splunk Observability Cloud app applies a poorly bounded regular expression to validate input submitted through one of its Representational State Transfer (REST) API endpoints, so crafted input can force excessive backtracking and consume disproportionate CPU. Splunk Enterprise exposes such endpoints declaratively through restmap.conf, and authorization is governed by Splunk's role-based access control model, which is why a low-privileged account that holds neither the 'admin' nor the 'power' role is sufficient - the endpoint is reachable to ordinary authenticated users. The CVSS vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H confirms the attacker is network-capable, requires low privileges, needs no user interaction, and achieves only high availability impact within the same security scope. The CPE cpe:2.3:a:splunk:splunk_enterprise:*:*:*:*:*:*:*:* is a broad wildcard, but the EUVD affected-version enumeration and the advisory narrow the real exposure to the 10.4, 10.2, and 10.0 release trains. Because the vulnerable surface belongs to a preview feature (Observability Cloud previews), deployments that never enabled or exposed that app are not on the attack path.

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Severity by source

Vendor (cisco) PRIMARY 6.5 MEDIUM
AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
vuln.today AI 6.5 MEDIUM

Remote REST endpoint (AV:N) with low complexity reachable by any authenticated low-privileged user (PR:L); ReDoS yields availability-only impact (A:H, C:N/I:N).

3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
4.0 AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Primary rating from Vendor (cisco).

CVSS VectorVendor: cisco

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

2
Patch available
Oct 07, 2026 - 22:02 EUVD
CVE Published
Oct 07, 2026 - 20:46 nvd
MEDIUM 6.5

DescriptionCVE.org

In Splunk Enterprise versions below 10.4.3, 10.2.7, and 10.0.10, a low-privileged user that does not hold the "admin" or "power" Splunk roles could cause a denial of service against a Representational State Transfer (REST) API endpoint in the Discover Splunk Observability Cloud app. The vulnerability is possible because the app uses an inefficient regular expression to validate input submitted through the endpoint. For more information see About configuring role-based user access (https://help.splunk.com/en/splunk-enterprise/administer/manage-users-and-security/10.4/manage-splunk-platform-users-and-roles/about-configuring-role-based-user-access), Splunk Observability Cloud previews (https://help.splunk.com/en/splunk-enterprise/search/search-manual/10.4/observability/splunk-observability-cloud-previews), and restmap.conf (https://help.splunk.com/en/splunk-enterprise/administer/admin-manual/10.4/configuration-file-reference/10.4.0-configuration-file-reference/restmap.conf) in the Splunk documentation.

Splunk Enterprise versions 9.4.x are not affected.

Threat Intelligence Overview

EPSS Score
0.3%
Top 83% exploitable
Prevalence
High
Splunk Enterprise is widely deployed enterprise SIEM/log platform
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 0.3%
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
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

32
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +32
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

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