CVE-2026-0621

Exploitation

Public exploit code exists. CISA's assessment records a public proof of concept. That is not a report of exploitation in the wild.

SSVC decision

• ExploitationpocPublic proof-of-concept exploit code exists. Not a report of exploitation in the wild.
• AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
• Technical ImpactpartialSuccessful exploitation gives limited 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

0.43% probability of exploitation activity in the next 30 days.

EPSS percentile

Equal to or higher than the score of 37.8% of scored records. A rank, not a probability.

NVD base score

8.7 (CVSS v4.0), scored by the NVD independently of the CNA.

NVD CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

NVD analysis status

Analyzed. NVD last modified this record on 2026-10-26.

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

2026-01-05 20:57Z9 MO AGO

Last updated

2026-10-08 15:21Z20 DAYS AGO

Reserved

2026-01-05

Assigning CNA

VulnCheck

Record state

PUBLISHED

Severity

High (CVSS 8.7)

CNA CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Weaknesses

• CWE-1333Inefficient Regular Expression ComplexityBase

Data version

5.2

Document digest

be771dab66f618c3006c0bc567cdb677b0372421ae4ae6d9a3e253971f1b6b85

• github.comhttps://github.com/modelcontextprotocol/typescript-sdk/issues/965issue-tracking
• www.vulncheck.comhttps://www.vulncheck.com/advisories/mcp-typescript-sdk-uritemplate-exploded-array-pattern-redosthird-party-advisory