CVE-2026-84637

Exploitation

Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.

SSVC decision

• ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
• AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
• Technical ImpacttotalSuccessful exploitation gives total control of the vulnerable component.

CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.

EPSS probability

0.62% probability of exploitation activity in the next 30 days.

EPSS percentile

Equal to or higher than the score of 49.8% of scored records. A rank, not a probability.

NVD base score

9.8 (CVSS v3.x), scored by the NVD independently of the CNA.

NVD CVSS vector

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

NVD analysis status

Analyzed. NVD last modified this record on 2026-09-03.

Red Hat severity

Important. Red Hat's rating for its own products, not a CVSS rating.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

Published

2026-09-01 21:25Z1 MO AGO

Last updated

2026-09-02 18:49Z1 MO AGO

Reserved

2026-09-01

Assigning CNA

mozilla

Record state

PUBLISHED

Severity

Critical (CVSS 9.8)

CNA CVSS vector

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

Weaknesses

• CWE-434Unrestricted Upload of File with Dangerous TypeBase
• CWE-59Improper Link Resolution Before File Access ('Link Following')Base

Data version

5.2

Document digest

e0765dc0e6dca2737b1e62146a21dbf59dc69d91c094932d3ffae51f143911bd

• bugzilla.mozilla.orghttps://bugzilla.mozilla.org/show_bug.cgi?id=2043878
• www.mozilla.orghttps://www.mozilla.org/security/advisories/mfsa2026-78/
• www.mozilla.orghttps://www.mozilla.org/security/advisories/mfsa2026-88/