What is CVE-2025-8760?

CVE-2025-8760 is a critical-severity vulnerability in Instar 2k+, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 9.8/10. Published 2025-08-13.

How severe is CVE-2025-8760?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Buffer overflow in Instar 2k+

CVE-2025-8760

A vulnerability was identified in INSTAR 2K+ and 4K 3.11.1 Build 1124. This affects the function base64_decode of the component fcgi_server. The manipulation of the argument Authorization leads to buffer overflow. It is possible to initiat…

Vulnerability class: Buffer Overflow

EPSS: 0.003 (51.5th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:X/RL:W/RC:R.

Affected products

Instar 2k+ — versions 3.11.1 Build 1124
Instar 4k — versions 3.11.1 Build 1124

Weakness classification (CWE)

References

VDB-319863 | INSTAR 2K+/4K fcgi_server base64_decode buffer overflow (vdb-entry, technical-description)
VDB-319863 | CTI Indicators (IOB, IOC, IOA) (signature, permissions-required)
modzero.com/static/MZ-25-03_modzero_INSTAR.pdf (related)

Frequently asked questions

What is CVE-2025-8760?: CVE-2025-8760 is a critical-severity vulnerability in Instar 2k+, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 9.8/10. Published 2025-08-13.
How severe is CVE-2025-8760?: Critical severity. CVSS v3 base score is 9.8 out of 10.