Weak webstax_auth Cookie Authentication Allows Privilege Escalation

published 2026-04-16 6 mo ago modified 2026-10-26 13 d ago also EUVD-2026-23272

cvss: 8.8; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 14%
public exploits: 0; none known

A privilege escalation vulnerability in Microchip IStaX allows an authenticated low-privileged user to recover a shared per-device cookie secret from their own webstax_auth session cookie and forge a new cookie with administrative privileges.This issue affects IStaX before 2026.03.

Patch / fix

fixed in 1

Microchip IStaX 2026.03

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: total
Assessed: 6 mo ago (2026-04-16)

Exploit prediction

0.23% chance of exploitation in the next 30 days, higher than 14% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	4.0	8.7	CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:H
CNA	4.0	8.7	CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:H/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	3.1	8.8	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

Microchip IStaX

Classification

Weakness

CWE-331 Insufficient Entropy

References

microchip.com /en-us/solutions/technologies/embedded-security/how-to-report-potential-product-security-vulnerabilities/istax
vendor-advisory, broken-link

Sources

CVE List CVE-2026-2336
NVD CVE-2026-2336

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary