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Fencer Vulns
medium 5.4

CVE-2021-33570 json

Postbird 0.8.4 allows stored XSS via the onerror attribute of an IMG element in any PostgreSQL database table.

published 2021-05-25 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-20258

cvss
5.4
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
3.6%
EPSS 3.6% chance of exploitation in 30 days, percentile 89%
public exploits
1
Exploit-DB

Summary

Postbird 0.8.4 allows stored XSS via the onerror attribute of an IMG element in any PostgreSQL database table. This can result in reading local files via vectors involving XMLHttpRequest and open of a file:/// URL, or discovering PostgreSQL passwords via vectors involving Window.localStorage and savedConnections.

Timeline

  1. Published
  2. First public exploit (EDB-49910)

Exploit prediction

3.56% chance of exploitation in the next 30 days, higher than 89% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • EDB-49910 Postbird 0.8.4 - Javascript Injection webapps, 2021-05-27
  • github.com https://github.com/Tridentsec-io/postbird referenced PoC, tagged "exploit" by a source, unverified
  • packetstormsecurity.com http://packetstormsecurity.com/files/162831/Postbird-0.8.4-Cross-Site-Scripting-Local-File-Inclusion.html referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
NVD 2.0 3.5 AV:N/AC:M/Au:S/C:N/I:P/A:N

Classification

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

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.