Medium severity · published May 12, 2026
CVE-2026-8391
Other issue in the JavaScript Engine component
5.3
CVSS
0.3%
EPSS
No
On KEV
Description
Other issue in the JavaScript Engine component. This vulnerability was fixed in Firefox 150.0.3, Firefox ESR 115.36, Firefox ESR 140.11, and Thunderbird 140.11.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
Low
Integrity
None
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 22% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
FI
Firefox · Mozilla
before 150.0.3 · source: NVD
RH
Red Hat Enterprise Linux 10 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 10.0 Extended Update Support · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 6 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 7 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 7 Extended Lifecycle Support · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 8 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 8.8 Telecommunications Update Service · Red Hat
All versions, or not specified · source: CISA
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-8391
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-8391
Permissions Required
https://bugzilla.mozilla.org/show_bug.cgi?id=2038575
Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-45/
www.mozilla.org
https://www.mozilla.org/security/advisories/mfsa2026-47/
www.mozilla.org
https://www.mozilla.org/security/advisories/mfsa2026-48/
www.mozilla.org
https://www.mozilla.org/security/advisories/mfsa2026-51/
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:21378
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