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Vulnerability details: VCID-bv2v-54kd-77a1
Vulnerability ID VCID-bv2v-54kd-77a1
Aliases CVE-2021-20254
Summary A flaw was found in samba. The Samba smbd file server must map Windows group identities (SIDs) into unix group ids (gids). The code that performs this had a flaw that could allow it to read data beyond the end of the array in the case where a negative cache entry had been added to the mapping cache. This could cause the calling code to return those values into the process token that stores the group membership for a user. The highest threat from this vulnerability is to data confidentiality and integrity.
Status Published
Exploitability 0.5
Weighted Severity 6.2
Risk 3.1
Affected and Fixed Packages Package Details
Weaknesses (1)
CWE-125 Out-of-bounds Read
System Score Found at
cvssv3 6.8 https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-20254.json
epss 0.00341 https://api.first.org/data/v1/epss?cve=CVE-2021-20254
epss 0.00341 https://api.first.org/data/v1/epss?cve=CVE-2021-20254
epss 0.00341 https://api.first.org/data/v1/epss?cve=CVE-2021-20254
epss 0.00341 https://api.first.org/data/v1/epss?cve=CVE-2021-20254
epss 0.00341 https://api.first.org/data/v1/epss?cve=CVE-2021-20254
epss 0.00341 https://api.first.org/data/v1/epss?cve=CVE-2021-20254
epss 0.00341 https://api.first.org/data/v1/epss?cve=CVE-2021-20254
epss 0.00341 https://api.first.org/data/v1/epss?cve=CVE-2021-20254
epss 0.00341 https://api.first.org/data/v1/epss?cve=CVE-2021-20254
epss 0.00341 https://api.first.org/data/v1/epss?cve=CVE-2021-20254
epss 0.00341 https://api.first.org/data/v1/epss?cve=CVE-2021-20254
epss 0.00341 https://api.first.org/data/v1/epss?cve=CVE-2021-20254
epss 0.00341 https://api.first.org/data/v1/epss?cve=CVE-2021-20254
epss 0.00341 https://api.first.org/data/v1/epss?cve=CVE-2021-20254
epss 0.00341 https://api.first.org/data/v1/epss?cve=CVE-2021-20254
epss 0.00389 https://api.first.org/data/v1/epss?cve=CVE-2021-20254
epss 0.00389 https://api.first.org/data/v1/epss?cve=CVE-2021-20254
epss 0.00389 https://api.first.org/data/v1/epss?cve=CVE-2021-20254
epss 0.00389 https://api.first.org/data/v1/epss?cve=CVE-2021-20254
epss 0.00389 https://api.first.org/data/v1/epss?cve=CVE-2021-20254
epss 0.00389 https://api.first.org/data/v1/epss?cve=CVE-2021-20254
epss 0.00389 https://api.first.org/data/v1/epss?cve=CVE-2021-20254
epss 0.00389 https://api.first.org/data/v1/epss?cve=CVE-2021-20254
epss 0.00389 https://api.first.org/data/v1/epss?cve=CVE-2021-20254
epss 0.00389 https://api.first.org/data/v1/epss?cve=CVE-2021-20254
cvssv3.1 7.1 https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
cvssv2 4.9 https://nvd.nist.gov/vuln/detail/CVE-2021-20254
cvssv3.1 6.8 https://nvd.nist.gov/vuln/detail/CVE-2021-20254
archlinux Medium https://security.archlinux.org/AVG-1893
Reference id Reference type URL
https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-20254.json
https://api.first.org/data/v1/epss?cve=CVE-2021-20254
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-20254
https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3EP2VJ73OVBPVSOSTVOMGIEQA3MWF6F7/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZAF6L2M6CNAJ2YYYGXPWETTW5YLCWTVT/
https://security.gentoo.org/glsa/202105-22
https://security.netapp.com/advisory/ntap-20210430-0001/
https://www.samba.org/samba/security/CVE-2021-20254.html
1949442 https://bugzilla.redhat.com/show_bug.cgi?id=1949442
987811 https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=987811
AVG-1893 https://security.archlinux.org/AVG-1893
cpe:2.3:a:samba:samba:*:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:samba:samba:*:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*
CVE-2021-20254 https://nvd.nist.gov/vuln/detail/CVE-2021-20254
RHSA-2021:2313 https://access.redhat.com/errata/RHSA-2021:2313
RHSA-2021:3723 https://access.redhat.com/errata/RHSA-2021:3723
RHSA-2021:3724 https://access.redhat.com/errata/RHSA-2021:3724
RHSA-2021:3988 https://access.redhat.com/errata/RHSA-2021:3988
RHSA-2021:4058 https://access.redhat.com/errata/RHSA-2021:4058
RHSA-2021:4866 https://access.redhat.com/errata/RHSA-2021:4866
USN-4930-1 https://usn.ubuntu.com/4930-1/
USN-4931-1 https://usn.ubuntu.com/4931-1/
No exploits are available.
Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N Found at https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-20254.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: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:L Found at https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
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:S/C:P/I:P/A:N Found at https://nvd.nist.gov/vuln/detail/CVE-2021-20254
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:H/PR:L/UI:N/S:U/C:H/I:H/A:N Found at https://nvd.nist.gov/vuln/detail/CVE-2021-20254
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 0.56144
EPSS Score 0.00341
Published At July 30, 2025, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2025-07-31T08:28:13.904764+00:00 Alpine Linux Importer Import https://secdb.alpinelinux.org/v3.16/main.json 37.0.0