CVE-2021-31999
CVE-2021-31999 is a high-severity vulnerability in Rancher with a CVSS 3.x base score of 8.8. 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-807.
Key facts
- Severity: High (CVSS 3.x base score 8.8)
- CVSS v2: 6.5
- EPSS exploit prediction: 1% (60th percentile)
- Actively exploited: Not listed in CISA KEV
- Weakness: CWE-807
- Affected product: Rancher
- Published:
- Last modified:
Description
A Reliance on Untrusted Inputs in a Security Decision vulnerability in Rancher allows users in the cluster to act as others users in the cluster by forging the "Impersonate-User" or "Impersonate-Group" headers. This issue affects: Rancher versions prior to 2.5.9. Rancher versions prior to 2.4.16.
Frequently asked questions
- What is CVE-2021-31999?
- A Reliance on Untrusted Inputs in a Security Decision vulnerability in Rancher allows users in the cluster to act as others users in the cluster by forging the "Impersonate-User" or "Impersonate-Group" headers. This issue affects: Rancher versions prior to 2.5.9. Rancher versions prior to 2.4.16.
- How severe is CVE-2021-31999?
- CVE-2021-31999 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
- Is CVE-2021-31999 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (60th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2021-31999?
- CVE-2021-31999 affects Rancher. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2021-31999?
- 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-2021-31999 published?
- CVE-2021-31999 was published on 2021-07-15 and last updated on 2026-06-17.
References
Affected products (1)
- cpe:2.3:a:rancher:rancher:*:*:*:*:*:*:*:*
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