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Fencer Vulns
medium 6.5

CVE-2021-38497 json

Through use of reportValidity() and window.open(), a plain-text validation message could have been overlaid on another origin, leading to p…

published 2021-11-03 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-24949

cvss
6.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 48%
public exploits
0
none known

Summary

Through use of reportValidity() and window.open(), a plain-text validation message could have been overlaid on another origin, leading to possible user confusion and spoofing attacks. This vulnerability affects Firefox < 93, Thunderbird < 91.2, and Firefox ESR < 91.2.

Patch / fix

  • Mozilla Firefox 93
  • Mozilla Thunderbird 91.2
  • Mozilla Firefox ESR 91.2
  • firefox Ubuntu 18.04 LTS 93.0+build1-0ubuntu0.18.04.1
  • firefox Ubuntu 20.04 LTS 93.0+build1-0ubuntu0.20.04.1
  • thunderbird Ubuntu 18.04 LTS 1:91.5.0+build1-0ubuntu0.18.04.1
  • thunderbird Ubuntu 20.04 LTS 1:91.5.0+build1-0ubuntu0.20.04.1
  • thunderbird Ubuntu 22.04 LTS 1:91.3.0+build2-0ubuntu1

ubuntu advisories UBUNTU-CVE-2021-38497

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • thunderbird RHEL 7 91.2.0-1.el7_9
  • thunderbird RHEL 8 91.2.0-1.el8_4
  • firefox RHEL 7 91.2.0-4.el7_9
  • firefox RHEL 8 91.2.0-4.el8_4
  • thunderbird RHEL 8.2 EUS 91.2.0-1.el8_2
  • thunderbird RHEL 8.1 EUS 91.2.0-1.el8_1
  • firefox RHEL 8.1 EUS 91.2.0-4.el8_1
  • firefox RHEL 8.2 EUS 91.2.0-4.el8_2

red hat advisories RHSA-2021:3839RHSA-2021:3841RHSA-2021:3838RHSA-2021:3840RHSA-2021:3791RHSA-2021:3757

  • MozillaThunderbird SLE Workstation Extension 15 SP3, SLE Workstation Extension 15 SP2 91.4.0-8.45.2
  • MozillaFirefox SLE Module for Desktop Applications 15 SP3, SLE Module for Desktop Applications 15 SP2 91.2.0-8.54.1
  • MozillaFirefox-branding-SLE SLE Module for Desktop Applications 15 SP3, SLE Module for Desktop Applications 15 SP2 91-9.5.1
  • MozillaFirefox SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +11 more 91.2.0-112.74.1
  • MozillaFirefox SLES for SAP 15 SP1, SLES for SAP 15, SLES 15-LTSS +7 more 91.2.0-3.155.2
  • MozillaFirefox-branding-SLE SLES for SAP 15 SP1, SLES for SAP 15, SLES 15-LTSS +7 more 91-4.19.1
  • MozillaFirefox SLES 11 SP4-LTSS 91.2.0-78.143.1
  • MozillaFirefox-branding-SLED SLES 11 SP4-LTSS 91-21.18.1

suse advisories SUSE-SU-2021:4150-1SUSE-SU-2021:14826-1SUSE-SU-2021:3451-1SUSE-SU-2021:3446-1SUSE-SU-2021:3331-1

  • firefox-esr openSUSE Tumbleweed 128.5.1-1.1
  • MozillaFirefox openSUSE Tumbleweed 93.0-1.1
  • MozillaThunderbird openSUSE Tumbleweed 91.2.0-1.1
  • MozillaThunderbird openSUSE Leap 15.2 91.4.0-lp152.2.52.1
  • MozillaThunderbird openSUSE Leap 15.3 91.4.0-8.45.2
  • MozillaFirefox openSUSE Leap 15.2 91.2.0-lp152.2.67.1
  • rust-cbindgen openSUSE Leap 15.2 0.19.0-lp152.2.7.1
  • MozillaFirefox openSUSE Leap 15.3 91.2.0-8.54.1

opensuse advisories openSUSE-SU-2024:14572-1openSUSE-SU-2024:11570-1openSUSE-SU-2024:11571-1openSUSE-SU-2021:1635-1openSUSE-SU-2021:4150-1openSUSE-SU-2021:1367-1

  • thunderbird Rocky Linux 8 91.2.0-1.el8_4
  • firefox Rocky Linux 8 91.2.0-4.el8_4

rocky linux advisories RLSA-2021:3838RLSA-2021:3755

  • firefox Alpine 3.23, Alpine 3.22, Alpine 3.21 +6 more 93.0-r0
  • librewolf Alpine 3.24, Alpine 3.23, Alpine 3.22 +1 more 93.0-r0
  • firefox-esr Alpine 3.23, Alpine 3.22, Alpine 3.21 +6 more 91.2.0-r0
  • thunderbird Alpine 3.23, Alpine 3.22, Alpine 3.21 +5 more 91.3.2-r0

alpine advisories ALPINE-CVE-2021-38497

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • firefox Arch Linux 93.0-1
  • thunderbird Arch Linux 91.2.0-1

arch linux advisories AVG-2443AVG-2459

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-38497 updated cvss 6.5

Mozilla: Validation message could have been overlaid on another origin

  • Red Hat Enterprise Linux 6 firefox, thunderbird
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux AppStream (v. 8) firefox 91.2.0-4.el8_4, thunderbird 91.2.0-1.el8_4
    fixed: vendor fix RHSA-2021:3755
  • Red Hat Enterprise Linux AppStream EUS (v. 8.1) firefox 91.2.0-4.el8_1, thunderbird 91.2.0-1.el8_1
    fixed: vendor fix RHSA-2021:3757
  • Red Hat Enterprise Linux AppStream EUS (v. 8.2) firefox 91.2.0-4.el8_2, thunderbird 91.2.0-1.el8_2
    fixed: vendor fix RHSA-2021:3756
  • Red Hat Enterprise Linux Client (v. 7) firefox 91.2.0-4.el7_9, thunderbird 91.2.0-1.el7_9 Red Hat Enterprise Linux Client Optional (v. 7) firefox 91.2.0-4.el7_9 Red Hat Enterprise Linux Server (v. 7) firefox 91.2.0-4.el7_9 Red Hat Enterprise Linux Server Optional (v. 7) firefox 91.2.0-4.el7_9, thunderbird 91.2.0-1.el7_9 Red Hat Enterprise Linux Workstation (v. 7) firefox 91.2.0-4.el7_9, thunderbird 91.2.0-1.el7_9 Red Hat Enterprise Linux Workstation Optional (v. 7) firefox 91.2.0-4.el7_9
    fixed: vendor fix RHSA-2021:3791

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.59% chance of exploitation in the next 30 days, higher than 48% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:P/A:N

Affected products

  • Mozilla Firefox
  • Mozilla Thunderbird
  • Mozilla Firefox ESR

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.