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Fencer Vulns
high 7.5

CVE-2021-33484 json

An issue was discovered in CommentsService.ashx in OnyakTech Comments Pro 3.8.

published 2021-09-07 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-20187

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.9%
EPSS 0.9% chance of exploitation in 30 days, percentile 59%
public exploits
0
none known

Summary

An issue was discovered in CommentsService.ashx in OnyakTech Comments Pro 3.8. An attacker can download a copy of the installer, decompile it, and discover a hardcoded IV used to encrypt the username and userid in the comment POST request. Additionally, the attacker can decrypt the encrypted encryption key (sent as a parameter in the comment form request) by setting this encrypted value as the username, which will appear on the comment page in its decrypted form. Using these two values (combined with the encryption functionality discovered in the decompiled installer), the attacker can encrypt another user's ID and username. These values can be used as part of the comment posting request in order to spoof the user.

Exploit prediction

0.89% chance of exploitation in the next 30 days, higher than 59% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • burninatorsec.blogspot.com https://burninatorsec.blogspot.com/2021/07/onyaktech-comments-pro-broken.html referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:P/I:N/A:N

Classification

Weakness
  • CWE-798 Use of Hard-coded Credentials

References

Sources

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.