How severe is CVE-2021-31559?

CVE-2021-31559 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2021-31559 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (53rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-31559?

CVE-2021-31559 primarily affects Splunk. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-31559?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-31559 published?

CVE-2021-31559 was published on 2022-05-06 and last updated on 2026-06-17.

CVE-2021-31559

CVE-2021-31559 is a high-severity vulnerability in Splunk with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-288.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 1% (53rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-288
Affected product: Splunk
Published: 2022-05-06
Last modified: 2026-06-17

Description

A crafted request bypasses S2S TCP Token authentication writing arbitrary events to an index in Splunk Enterprise Indexer 8.1 versions before 8.1.5 and 8.2 versions before 8.2.1. The vulnerability impacts Indexers configured to use TCPTokens. It does not impact Universal Forwarders.

Frequently asked questions

What is CVE-2021-31559?: A crafted request bypasses S2S TCP Token authentication writing arbitrary events to an index in Splunk Enterprise Indexer 8.1 versions before 8.1.5 and 8.2 versions before 8.2.1. The vulnerability impacts Indexers configured to use TCPTokens. It does not impact Universal Forwarders.
How severe is CVE-2021-31559?: CVE-2021-31559 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2021-31559 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (53rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-31559?: CVE-2021-31559 primarily affects Splunk. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-31559?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-31559 published?: CVE-2021-31559 was published on 2022-05-06 and last updated on 2026-06-17.

References

https://www.splunk.com/en_us/product-security/announcements/svd-2022-0503.html

Affected products (2)

cpe:2.3:a:splunk:splunk:*:*:*:*:enterprise:*:*:*
cpe:2.3:a:splunk:splunk:8.2.0:*:*:*:enterprise:*:*:*

More vulnerabilities in Splunk

CVE-2026-20253 — Critical (CVSS 9.8): In Splunk Enterprise 10.2 versions below 10.2.4 and 10 versions below 10.0.7, an unauthenticated user could create or…
CVE-2017-17067 — Critical (CVSS 9.8): Splunk Web in Splunk Enterprise 7.0.x before 7.0.0.1, 6.6.x before 6.6.3.2, 6.5.x before 6.5.6, 6.4.x before 6.4.9, and…
CVE-2016-10126 — Critical (CVSS 9.8): Splunk Web in Splunk Enterprise 5.0.x before 5.0.17, 6.0.x before 6.0.13, 6.1.x before 6.1.12, 6.2.x before 6.2.12,…
CVE-2013-6771 — Critical (CVSS 9.3): Directory traversal vulnerability in the collect script in Splunk before 5.0.5 allows remote attackers to execute…
CVE-2011-4644 — Critical (CVSS 9.3): Splunk 4.2.5 and earlier, when a Free license is selected, enables potentially undesirable functionality within an…
CVE-2022-32158 — Critical (CVSS 9.0): Splunk Enterprise deployment servers in versions before 8.1.10.1, 8.2.6.1, and 9.0 let clients deploy forwarder bundles…

All CVEs affecting Splunk →

Other CWE-288 vulnerabilities

CVE-2026-53622 — Critical (CVSS 10.0): Traefik is an HTTP reverse proxy and load balancer. Prior to 3.7.3, there is a critical vulnerability in Traefik's…
CVE-2026-48491 — Critical (CVSS 10.0): Traefik is an HTTP reverse proxy and load balancer. From 3.7.0 until 3.7.3, there is a high severity vulnerability in…
CVE-2026-48020 — Critical (CVSS 10.0): Traefik is an HTTP reverse proxy and load balancer. Prior to 2.11.48, 3.6.19, and 3.7.3, there is a high severity…
CVE-2026-20079 — Critical (CVSS 10.0): A vulnerability in the web interface of Cisco Secure Firewall Management Center (FMC) Software could allow an…
CVE-2024-10081 — Critical (CVSS 10.0): CodeChecker is an analyzer tooling, defect database and viewer extension for the Clang Static Analyzer and Clang Tidy.…
CVE-2024-2973 — Critical (CVSS 10.0): An Authentication Bypass Using an Alternate Path or Channel vulnerability in Juniper Networks Session Smart Router or…

Browse all CWE-288 vulnerabilities →