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Fencer Intel
high 8.7

CVE-2021-42083 json

Authenticated Stored XSS in OSNEXUS QuantaStor 6.0.0.335

published 3y ago modified 4mo ago also EUVD-2021-29069

cvss
8.7
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 46%
public exploits
0
none known

Summary

An authenticated attacker is able to create alerts that trigger a stored XSS attack.

POC

* go to the alert manager

* open the ITSM tab * add a webhook with the URL/service token value

' -h && id | tee /tmp/ttttttddddssss #' (whitespaces are tab characters)

* click add

* click apply

* create a test alert

* The test alert will run the command

“id | tee /tmp/ttttttddddssss” as root.

* after the test alert inspect

/tmp/ttttttddddssss it'll contain the ids of the root user.

Patch / fix

  • OSNEXUS QuantaStor 6.0.0.355

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Exploit prediction

0.55% chance of exploitation in the next 30 days, higher than 46% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • wbsec.nl https://www.wbsec.nl/osnexus referenced PoC, tagged "exploit" by a source, unverified
  • csirt.divd.nl https://csirt.divd.nl/CVE-2021-42083 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 8.7 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N
NVD 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Affected products

  • OSNEXUS QuantaStor

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

Fencer Intel 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.