9.8

CVE-2021-31921: istio Missing Authorization

CVSS: 9.8v3.1CriticalModified
AliasesRHSA-2021:2061RHSA-2021:2085
Published 02-06-2021Last modified 03-08-2024
Open JSON

Vulnerability summary

CVE-2021-31921 is a critical (CVSS 9.8) Missing Authorization vulnerability in istio. EPSS estimates a 1.45% chance of exploitation in the next 30 days, higher than 73% of scored vulnerabilities. 1 public exploit is recorded.

Overall risk
70/100
0100
High · default modelHow is this calculated?
CVSS score
9.8/10
010
Critical · v3.1 (NVD)
EPSS score
1.45%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits1reference

Timeline

  1. 02-06-2021
    PublishedVulnerability first disclosed.
  2. 03-08-2024
    Last modifiedVulnerability information updated.

Description

Istio before 1.8.6 and 1.9.x before 1.9.5 contains a remotely exploitable vulnerability where an external client can access unexpected services in the cluster, bypassing authorization checks, when a gateway is configured with AUTO_PASSTHROUGH routing configuration.

CVSS metrics

3 scores · 2 sources · 2 versions

EPSS trend

Probability

1.45%

Chance of exploitation in the next 30 days

Percentile

73%

Versus all other CVEs

30-day change

0.00 pp

From 1.45% on 19-09-2026

19-09-202619-10-2026
EPSS score
1.45%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

1 found
  • referenceUnverified

    Exploit Reference (istio.io)

    Maturity: unknown

Weaknesses

CWE · root cause

Affected systems

Redhat9 products
  • servicemesh< 0:2.0.5-3.el8 | < 0:1.1.15-4.el8
  • servicemesh-citadel< 0:1.1.15-4.el8
  • servicemesh-galley< 0:1.1.15-4.el8
  • servicemesh-istioctl< 0:2.0.5-3.el8 | < 0:1.1.15-4.el8
  • servicemesh-mixc< 0:2.0.5-3.el8 | < 0:1.1.15-4.el8
Istio1 product
  • istio< 1.8.6 | ≥ 1.9.0, < 1.9.5

2 vendors · 10 products

References

10 links