Search for vulnerabilities
Vulnerability details: VCID-kkes-taub-zucz
Vulnerability ID VCID-kkes-taub-zucz
Aliases CVE-2021-23969
Summary As specified in the W3C Content Security Policy draft, when creating a violation report, "User agents need to ensure that the source file is the URL requested by the page, pre-redirects. If that’s not possible, user agents need to strip the URL down to an origin to avoid unintentional leakage." Under certain types of redirects, Thunderbird incorrectly set the source file to be the destination of the redirects. This was fixed to be the redirect destination's origin.
Status Published
Exploitability 0.5
Weighted Severity 8.0
Risk 4.0
Affected and Fixed Packages Package Details
Weaknesses (1)
CWE-200 Exposure of Sensitive Information to an Unauthorized Actor
System Score Found at
cvssv3 4.3 https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-23969.json
epss 0.01163 https://api.first.org/data/v1/epss?cve=CVE-2021-23969
epss 0.01163 https://api.first.org/data/v1/epss?cve=CVE-2021-23969
epss 0.01163 https://api.first.org/data/v1/epss?cve=CVE-2021-23969
epss 0.01163 https://api.first.org/data/v1/epss?cve=CVE-2021-23969
epss 0.01163 https://api.first.org/data/v1/epss?cve=CVE-2021-23969
epss 0.01163 https://api.first.org/data/v1/epss?cve=CVE-2021-23969
epss 0.01163 https://api.first.org/data/v1/epss?cve=CVE-2021-23969
epss 0.01163 https://api.first.org/data/v1/epss?cve=CVE-2021-23969
epss 0.01163 https://api.first.org/data/v1/epss?cve=CVE-2021-23969
epss 0.01163 https://api.first.org/data/v1/epss?cve=CVE-2021-23969
epss 0.01163 https://api.first.org/data/v1/epss?cve=CVE-2021-23969
epss 0.01163 https://api.first.org/data/v1/epss?cve=CVE-2021-23969
epss 0.01163 https://api.first.org/data/v1/epss?cve=CVE-2021-23969
epss 0.01163 https://api.first.org/data/v1/epss?cve=CVE-2021-23969
epss 0.01163 https://api.first.org/data/v1/epss?cve=CVE-2021-23969
cvssv3.1 4.3 https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
cvssv2 4.3 https://nvd.nist.gov/vuln/detail/CVE-2021-23969
cvssv3.1 4.3 https://nvd.nist.gov/vuln/detail/CVE-2021-23969
archlinux High https://security.archlinux.org/AVG-1599
archlinux High https://security.archlinux.org/AVG-1601
generic_textual high https://www.mozilla.org/en-US/security/advisories/mfsa2021-07
generic_textual high https://www.mozilla.org/en-US/security/advisories/mfsa2021-08
generic_textual high https://www.mozilla.org/en-US/security/advisories/mfsa2021-09
Reference id Reference type URL
https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-23969.json
https://api.first.org/data/v1/epss?cve=CVE-2021-23969
https://bugzilla.mozilla.org/show_bug.cgi?id=1542194
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-23968
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-23969
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-23973
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-23978
https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
https://lists.debian.org/debian-lts-announce/2021/03/msg00000.html
https://security.gentoo.org/glsa/202104-09
https://security.gentoo.org/glsa/202104-10
https://www.debian.org/security/2021/dsa-4866
https://www.mozilla.org/security/advisories/mfsa2021-07/
https://www.mozilla.org/security/advisories/mfsa2021-08/
https://www.mozilla.org/security/advisories/mfsa2021-09/
1932109 https://bugzilla.redhat.com/show_bug.cgi?id=1932109
AVG-1599 https://security.archlinux.org/AVG-1599
AVG-1601 https://security.archlinux.org/AVG-1601
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
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:*:*:*:*:*:*:*
CVE-2021-23969 https://nvd.nist.gov/vuln/detail/CVE-2021-23969
mfsa2021-07 https://www.mozilla.org/en-US/security/advisories/mfsa2021-07
mfsa2021-08 https://www.mozilla.org/en-US/security/advisories/mfsa2021-08
mfsa2021-09 https://www.mozilla.org/en-US/security/advisories/mfsa2021-09
RHSA-2021:0655 https://access.redhat.com/errata/RHSA-2021:0655
RHSA-2021:0656 https://access.redhat.com/errata/RHSA-2021:0656
RHSA-2021:0657 https://access.redhat.com/errata/RHSA-2021:0657
RHSA-2021:0658 https://access.redhat.com/errata/RHSA-2021:0658
RHSA-2021:0659 https://access.redhat.com/errata/RHSA-2021:0659
RHSA-2021:0660 https://access.redhat.com/errata/RHSA-2021:0660
RHSA-2021:0661 https://access.redhat.com/errata/RHSA-2021:0661
RHSA-2021:0662 https://access.redhat.com/errata/RHSA-2021:0662
USN-4756-1 https://usn.ubuntu.com/4756-1/
USN-4936-1 https://usn.ubuntu.com/4936-1/
No exploits are available.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N Found at https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-23969.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:L/PR:N/UI:R/S:U/C:L/I:N/A:N 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:N/C:P/I:N/A:N Found at https://nvd.nist.gov/vuln/detail/CVE-2021-23969
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:R/S:U/C:L/I:N/A:N Found at https://nvd.nist.gov/vuln/detail/CVE-2021-23969
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 0.77731
EPSS Score 0.01163
Published At July 30, 2025, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2025-07-31T08:09:47.172433+00:00 Mozilla Importer Import https://github.com/mozilla/foundation-security-advisories/blob/master/announce/2021/mfsa2021-09.yml 37.0.0