VDB

CVE-2026-6771

CVE-2026-6771 PUBLISHED CVSS 9.8 CRITICAL

Mitigation bypass in the DOM: Security component

Reported by mozilla · Published April 21, 2026

Mitigation bypass in the DOM: Security component. This vulnerability was fixed in Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10.

Fixed versions

Upgrade to a fixed version or later. Language registries are listed first, then Linux distributions, then vendor products.

PackageEcosystemFixed in
firefoxerrata.rockylinux.org140.10.0-1.el9, 140.10.0-1.el8, 140.10.0-1.el10, 0:140.10.0-1.el9_7.x86_64, 0:140.10.0-1.el9_7.src, 0:140.10.0-1.el9_7.s390x, 0:140.10.0-1.el9_7.ppc64le, 0:140.10.0-1.el9_7.aarch64, 0:140.10.0-1.el8_10.x86_64, 0:140.10.0-1.el8_10.src, 0:140.10.0-1.el8_10.aarch64, 0:140.10.0-1.el10_1.x86_64, 0:140.10.0-1.el10_1.src, 0:140.10.0-1.el10_1.s390x, 0:140.10.0-1.el10_1.ppc64le, 0:140.10.0-1.el10_1.aarch64
firefox-x11errata.rockylinux.org140.10.0-1.el9, 0:140.10.0-1.el9_7.x86_64, 0:140.10.0-1.el9_7.s390x, 0:140.10.0-1.el9_7.ppc64le, 0:140.10.0-1.el9_7.aarch64
firefoxWolfi140.10-r0
firefox-debuginfoerrata.rockylinux.org140.10.0-1.el9, 140.10.0-1.el8, 140.10.0-1.el10, 0:140.10.0-1.el9_7.x86_64, 0:140.10.0-1.el9_7.s390x, 0:140.10.0-1.el9_7.ppc64le, 0:140.10.0-1.el9_7.aarch64, 0:140.10.0-1.el8_10.x86_64, 0:140.10.0-1.el8_10.aarch64, 0:140.10.0-1.el10_1.x86_64, 0:140.10.0-1.el10_1.s390x, 0:140.10.0-1.el10_1.ppc64le, 0:140.10.0-1.el10_1.aarch64
thunderbird-debuginfoerrata.rockylinux.org140.10.1-1.el9, 140.10.0-1.el9, 140.10.0-1.el8, 140.10.0-1.el10, 0:140.10.0-1.el8_10.x86_64, 0:140.10.0-1.el8_10.aarch64, 0:140.10.0-1.el10_1.x86_64, 0:140.10.0-1.el10_1.s390x, 0:140.10.0-1.el10_1.ppc64le, 0:140.10.0-1.el10_1.aarch64
thunderbirderrata.rockylinux.org140.10.1-1.el9, 140.10.0-1.el9, 140.10.0-1.el8, 140.10.0-1.el10, 0:140.10.0-1.el8_10.x86_64, 0:140.10.0-1.el8_10.src, 0:140.10.0-1.el8_10.aarch64, 0:140.10.0-1.el10_1.x86_64, 0:140.10.0-1.el10_1.src, 0:140.10.0-1.el10_1.s390x, 0:140.10.0-1.el10_1.ppc64le, 0:140.10.0-1.el10_1.aarch64
firefox-debugsourceerrata.rockylinux.org140.10.0-1.el9, 140.10.0-1.el8, 140.10.0-1.el10, 0:140.10.0-1.el9_7.x86_64, 0:140.10.0-1.el9_7.s390x, 0:140.10.0-1.el9_7.ppc64le, 0:140.10.0-1.el9_7.aarch64, 0:140.10.0-1.el8_10.x86_64, 0:140.10.0-1.el8_10.aarch64, 0:140.10.0-1.el10_1.x86_64, 0:140.10.0-1.el10_1.s390x, 0:140.10.0-1.el10_1.ppc64le, 0:140.10.0-1.el10_1.aarch64
thunderbird-debugsourceerrata.rockylinux.org140.10.1-1.el9, 140.10.0-1.el9, 140.10.0-1.el8, 140.10.0-1.el10, 0:140.10.0-1.el8_10.x86_64, 0:140.10.0-1.el8_10.aarch64, 0:140.10.0-1.el10_1.x86_64, 0:140.10.0-1.el10_1.s390x, 0:140.10.0-1.el10_1.ppc64le, 0:140.10.0-1.el10_1.aarch64
firefoxAmazon Linux140.10.1-1.amzn2023.0.1
firefoxChainguard140.10-r0
firefox-esrChainguard140.10-r0, 140.10.1-r0
thunderbirdAmazon Linux140.10.0-1.amzn2.0.1

2 more packages have a fixed version. See every fix in Lookup.

Risk scores

CVSS 3.1
9.8
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

VendorProductVersions
MozillaFirefox140.10, 150
MozillaThunderbird140.10, 150
wolfifirefox0
amazon:2023firefox0
MozillaThunderbird150, 140.10
MozillaFirefox150, 140.10
chainguardfirefox0
chainguardfirefox-esr0, 0
amazon:2thunderbird0

Timeline

  • Apr 21, 2026 CVE Published
  • Apr 22, 2026 EPSS Score (30 in total, the first dated here)
  • Apr 22, 2026 Security Advisory (34 in total, the first dated here)
  • Apr 28, 2026 Distribution Patch (37 in total, the first dated here)
  • Jul 14, 2026 Coalition ESS Score

Query this with the API

The same record, from the CLI:

vulnetix vdb vuln CVE-2026-6771
vulnetix vdb fixes CVE-2026-6771

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curl -s -H "Authorization: ApiKey ${VULNETIX_ORG_ID}:${VULNETIX_API_KEY}" \
  "https://api.vdb.vulnetix.com/v2/vuln/CVE-2026-6771/fixes/registry"

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References

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