Splunk Enterprise: Improper Neutralization of Null Byte or NUL Character
CVE-2026-76354 is a high-severity improper neutralization of null byte or NUL character vulnerability in Splunk Enterprise from Splunk, with a CVSS 3.1 base score of 8.1 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. The record lists versions 10.4.2, 10.2.6, 10.0.9 as the first without the flaw, so updating Splunk Enterprise to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.44% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Splunk Enterprise to 10.4.2 or 10.2.6 or 10.0.9 or 9.4.14, whichever matches your release line, or a later version.
- Update Splunk to 9.4.14 or 10.0.9 or 10.2.6 or 10.4.2, whichever matches your release line, or a later version.
- Read the advisory on advisory.splunk.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Splunk | Splunk Enterprise | 10.4 up to, but not including, 10.4.2; 10.2 up to, but not including, 10.2.6; 10.0 up to, but not including, 10.0.9; 9.4 up to, but not including, 9.4.14 | 10.4.2, 10.2.6, 10.0.9, 9.4.14 |
| Splunk | Splunk | 9.4.0 up to, but not including, 9.4.14; 10.0.0 up to, but not including, 10.0.9; 10.2.0 up to, but not including, 10.2.6; 10.4.0 up to, but not including, 10.4.2 | 9.4.14, 10.0.9, 10.2.6, 10.4.2 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H. Scored by CNA (cisco.com).
Official description
In Splunk Enterprise versions below 10.4.2, 10.2.6, 10.0.9, and 9.4.14, a user who does not hold the "admin" or "power" Splunk roles could affect system integrity and availability by sending a crafted Representational State Transfer (REST) API request that deletes or temporarily overwrites files writable by the user account running Splunk Enterprise processes on a non-captain search head cluster member. The vulnerability is possible because Search Head Clustering bundle replication does not validate the name of a replicated bundle file or neutralize NUL bytes before constructing the member bundle path. For more information see About search head clustering (https://help.splunk.com/en/splunk-enterprise/administer/distributed-search/10.4/overview-of-search-head-clustering/about-search-head-clustering), Define roles on the Splunk platform with capabilities (https://help.splunk.com/en/splunk-enterprise/administer/manage-users-and-security/10.4/manage-splunk-platform-users-and-roles/define-roles-on-the-splunk-platform-with-capabilities), and Secure Splunk Enterprise service accounts (https://help.splunk.com/en/splunk-enterprise/administer/manage-users-and-security/9.0/install-splunk-enterprise-securely/secure-splunk-enterprise-service-accounts) in the Splunk documentation.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Neutralization of Null Byte or NUL Character
The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes NUL characters or null bytes when they are sent to a downstream component.
How developers prevent this class of flaw
- Developers should anticipate that null characters or null bytes will be injected/removed/manipulated in the input vectors of their product. Use an appropriate combination of denylists and allowlists to ensure only valid, expected and appropriate input is processed by the system.
- Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.
More Improper Neutralization of Null Byte or NUL Character vulnerabilities (CWE-158)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Other vulnerabilities in Splunk Enterprise
- 9.9 Critical severity
- 9.8 Critical severity
- 8.8 High severity
- 9.9 Critical severity
- 8.8 High severity
- 7.2 High severity
Recent Improper Neutralization of Null Byte or NUL Character vulnerabilities
- 8.6 High severity
- 9.8 Critical severity
- 7.5 High severity
- 8.7 High severity
- 10.0 Critical severity
- 10.0 Critical severity
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