Splunk Enterprise: Deserialization of Untrusted Data
CVE-2026-20251 is a high-severity deserialization of untrusted data vulnerability in Splunk Enterprise from Splunk, with a CVSS 3.1 base score of 8.8 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 10.2.4, 10.0.7, 9.4.12 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 30.6% chance of exploitation within 30 days, which is in the top 1.73% of all scored CVEs.
EPSS places it among the vulnerabilities most likely to be exploited soon.
What to do
- Update Splunk Enterprise to 10.2.4 or 10.0.7 or 9.4.12 or 9.3.13, whichever matches your release line, or a later version.
- Update Splunk Cloud Platform to 10.3.2512.12 or 10.2.2510.14 or 10.1.2507.22 or 9.3.2411.132, whichever matches your release line, or a later version.
- Update Splunk Secure Gateway to 3.10.6 or 3.9.20 or 3.8.67, 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 | 10.2 up to, but not including, 10.2.4; 10.0 up to, but not including, 10.0.7; 9.4 up to, but not including, 9.4.12; 9.3 up to, but not including, 9.3.13 | 10.2.4, 10.0.7, 9.4.12, 9.3.13 |
| Splunk | Splunk Cloud Platform | 10.3.2512 up to, but not including, 10.3.2512.12; 10.2.2510 up to, but not including, 10.2.2510.14; 10.1.2507 up to, but not including, 10.1.2507.22; 9.3.2411 up to, but not including, 9.3.2411.132 | 10.3.2512.12, 10.2.2510.14, 10.1.2507.22, 9.3.2411.132 |
| Splunk | Splunk Secure Gateway | 3.10 up to, but not including, 3.10.6; 3.9 up to, but not including, 3.9.20; 3.8 up to, but not including, 3.8.67 | 3.10.6, 3.9.20, 3.8.67 |
| Splunk | Splunk | 9.3.0 up to, but not including, 9.3.13; 9.4.0 up to, but not including, 9.4.12; 10.0.0 up to, but not including, 10.0.7; 10.2.0 up to, but not including, 10.2.4 | 9.3.13, 9.4.12, 10.0.7, 10.2.4 |
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
- HighAll data handled by the component can be read.
- 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:H/I:H/A:H. Scored by CNA (cisco.com).
Official description
In Splunk Enterprise versions below 10.2.4, 10.0.7, 9.4.12, and 9.3.13, Splunk Cloud Platform versions below 10.3.2512.12, 10.2.2510.14, 10.1.2507.22, and 9.3.2411.132, and Splunk Secure Gateway versions below 3.10.6, 3.9.20, and 3.8.67, a low-privileged user that does not hold the 'admin' or 'power' Splunk roles could perform a Remote Code Execution (RCE) through the Splunk Secure Gateway app.<br><br>The Remote Code Execution is possible because of unsafe deserialization of App Key Value Store (KV Store) data through the ‘jsonpickle’ Python library, which reconstructs arbitrary Python objects from specially crafted JavaScript Object Notation (JSON) without adequate validation.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Deserialization of Untrusted Data
The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.
How developers prevent this class of flaw
- If available, use the signing/sealing features of the programming language to assure that deserialized data has not been tainted. For example, a hash-based message authentication code (HMAC) could be used to ensure that data has not been modified.
- When deserializing data, populate a new object rather than just deserializing. The result is that the data flows through safe input validation and that the functions are safe.
- Explicitly define a final object() to prevent deserialization.
More Deserialization of Untrusted Data vulnerabilities (CWE-502)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- 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 Deserialization of Untrusted Data vulnerabilities
- 8.8 High severity
- 8.8 High severity
- 8.4 High severity
- 8.1 High severity
- 8.1 High severity
- 7.2 High severity
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