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Fencer Intel
high 7.7

CVE-2021-39195 json

Server-Side Request Forgery vulnerability in misskey

published 5y ago modified 4mo ago also EUVD-2021-25580

cvss
7.7
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.1%
EPSS 1.1% chance of exploitation in 30 days, percentile 64%
public exploits
0
none known

Summary

Misskey is an open source, decentralized microblogging platform. In affected versions a Server-Side Request Forgery vulnerability exists in "Upload from URL" and remote attachment handling. This could result in the disclosure of non-public information within the internal network. This has been fixed in 12.90.0. However, if you are using a proxy, you will need to take additional measures. As a workaround this exploit may be avoided by appropriately restricting access to private networks from the host where the application is running.

Patch / fix

  • misskey misskey 12.90.0

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Exploit prediction

1.06% chance of exploitation in the next 30 days, higher than 64% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 7.7 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
NVD 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
NVD 2.0 4.0 AV:N/AC:L/Au:S/C:P/I:N/A:N

Affected products

  • misskey-dev misskey

Classification

Weakness
  • CWE-918 Server-Side Request Forgery

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.