CVE-2026-6556

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

0.52% probability of exploitation activity in the next 30 days.

EPSS percentile

Equal to or higher than the score of 43.9% of scored records. A rank, not a probability.

NVD base score

9.1 (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:N

NVD analysis status

Analyzed. NVD last modified this record on 2026-07-01.

Red Hat severity

No Red Hat rating. Red Hat rates the CVEs that affect its products.

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

2026-06-30 12:48Z4 MO AGO

Last updated

2026-06-30 13:30Z4 MO AGO

Reserved

2026-04-18

Assigning CNA

openjs

Record state

PUBLISHED

Severity

Critical (CVSS 9.1)

CNA CVSS vector

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

Weaknesses

• CWE-285Improper AuthorizationClass

Data version

5.2

Document digest

69d6a331f7bf52a859be5b087ed98715ce69b16c6e967c1f8ce3d0c07070a3a6

• github.comhttps://github.com/fastify/fastify-express/security/advisories/GHSA-3wf5-7852-vcfq
• cna.openjsf.orghttps://cna.openjsf.org/security-advisories.html