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Vulnerability details: VCID-fhr4-2cw2-aaaj
Vulnerability ID VCID-fhr4-2cw2-aaaj
Aliases CVE-2021-31921
Summary 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.
Status Published
Exploitability 0.5
Weighted Severity 9.0
Risk 4.5
Affected and Fixed Packages Package Details
Weaknesses (2)
CWE-862 Missing Authorization
CWE-863 Incorrect Authorization
System Score Found at
rhas Important https://access.redhat.com/errata/RHSA-2021:2061
rhas Important https://access.redhat.com/errata/RHSA-2021:2085
cvssv3 10.0 https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-31921.json
epss 0.00153 https://api.first.org/data/v1/epss?cve=CVE-2021-31921
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rhbs high https://bugzilla.redhat.com/show_bug.cgi?id=1955396
cvssv2 6.8 https://nvd.nist.gov/vuln/detail/CVE-2021-31921
cvssv3 9.8 https://nvd.nist.gov/vuln/detail/CVE-2021-31921
cvssv3.1 9.8 https://nvd.nist.gov/vuln/detail/CVE-2021-31921
archlinux Critical https://security.archlinux.org/AVG-1947
Reference id Reference type URL
https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-31921.json
https://api.first.org/data/v1/epss?cve=CVE-2021-31921
https://istio.io/latest/news/security/istio-security-2021-006/
1955396 https://bugzilla.redhat.com/show_bug.cgi?id=1955396
AVG-1947 https://security.archlinux.org/AVG-1947
cpe:2.3:a:istio:istio:*:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:istio:istio:*:*:*:*:*:*:*:*
CVE-2021-31921 https://nvd.nist.gov/vuln/detail/CVE-2021-31921
ISTIO-SECURITY-2021-006 https://istio.io/latest/news/security/ISTIO-SECURITY-2021-006/
RHSA-2021:2061 https://access.redhat.com/errata/RHSA-2021:2061
RHSA-2021:2085 https://access.redhat.com/errata/RHSA-2021:2085
No exploits are available.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H Found at https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-31921.json
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: AV:N/AC:M/Au:N/C:P/I:P/A:P Found at https://nvd.nist.gov/vuln/detail/CVE-2021-31921
Exploitability (E) Access Vector (AV) Access Complexity (AC) Authentication (Au) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

high

functional

unproven

proof_of_concept

not_defined

local

adjacent_network

network

high

medium

low

multiple

single

none

none

partial

complete

none

partial

complete

none

partial

complete
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Found at https://nvd.nist.gov/vuln/detail/CVE-2021-31921
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Found at https://nvd.nist.gov/vuln/detail/CVE-2021-31921
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Exploit Prediction Scoring System (EPSS)
Percentile 0.32717
EPSS Score 0.00153
Published At March 28, 2025, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
There are no relevant records.