CVE-2021-33570

Exp

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.

Published: 2021-05-25 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-33570 is rated High Exploit Risk (70.2/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 3.56%). 4 public exploit reference(s) are indexed (Exploit-DB). EPSS rose +2.87% over the last day, indicating growing attacker interest. Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2021-33570

EDB-ID Source Kind Published Link
49910 exploit_db edb 2021-05-27 Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2021-33570

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.69% 3.56% +2.87%
2 2026-05-08 1.71% 0.69% -1.02%
3 2025-11-21 — 1.71% —

Full EPSS history (24 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-33570

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.4 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 2.3 2.7 [email protected]
3.5 2.0 LOW
AV:N/AC:M/Au:S/C:N/I:P/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:S)
A single authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:N)
No availability impact.
 6.8 2.9 [email protected]

Weakness enumeration for CVE-2021-33570

Affected software / configurations for CVE-2021-33570

Vendor Product Version Raw CPE
postbird_project postbird 0.8.4 cpe:2.3:a:postbird_project:postbird:0.8.4:*:*:*:*:*:*:*

References for CVE-2021-33570

URL Tags
http://packetstormsecurity.com/files/162831/Postbird-0.8.4-Cross-Site-Scripting-Local-File-Inclusion.html Exploit Third Party Advisory VDB Entry
http://packetstormsecurity.com/files/162872/Postbird-0.8.4-XSS-LFI-Insecure-Data-Storage.html Third Party Advisory VDB Entry
https://github.com/Paxa/postbird/issues/132 Issue Tracking Third Party Advisory
https://github.com/Paxa/postbird/issues/133 Issue Tracking Third Party Advisory
https://github.com/Paxa/postbird/issues/134 Issue Tracking Third Party Advisory
https://github.com/Tridentsec-io/postbird Exploit Third Party Advisory
https://tridentsec.io/blogs/postbird-cve-2021-33570/ Broken Link Third Party Advisory URL Repurposed
https://www.exploit-db.com/exploits/49910 Exploit Third Party Advisory VDB Entry
cvelogic Threat Intelligence