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CVE-2026-21859

31
FAUCET Score

CVE-2026-21859 describes a Server-Side Request Forgery (SSRF) vulnerability in Mailpit versions 1.28.0 and below, an email testing tool. Attackers can exploit the /proxy endpoint to make HTTP GET requests to internal network resources, bypassing scheme validation for internal IP addresses. This vulnerability has a CVSS score of 5.3 (Medium), indicating low attack complexity and no user interaction, but only allows for limited information disclosure. While there are no known active exploits or Metasploit modules, Nuclei templates exist, and the vulnerability has garnered some community discussion, suggesting potential for future exploitation.

Impacted Technologies

VendorProductVersion(s)CPE
< 1.28.1CPE matchmatch criteria
cpe:2.3:a:axllent:mailpit:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

5.8MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
LOW
Integrity Impact
NONE
Availability Impact
NONE
Exploitability Score
3.9
Impact Score
1.4
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.76%
Probability of exploitation in next 30 days
EPSS Percentile
51.3%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
Nuclei: CVE-2026-21859 · Jan 21, 2026
This CVE's current EPSS score of 0.0076 is in the 32nd percentile among its peer group of 23,705 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

github_advisorypatch availablevia nvd_reference
View patch
gopatch availablevia ghsa
Product: github.com/axllent/mailpitFixed in: 1.28.1

Vendor Advisories (1)

goGHSA-8v65-47jx-7mfrmedium

Mailpit Proxy Endpoint has Server-Side Request Forgery (SSRF) vulnerability

Jan 6, 2026

References

github.com / axllent/mailpit/commit/3b9b470c093b3d20b7d751722c1c24f3eed2e19d
Patch
github.com / axllent/mailpit/security/advisories/GHSA-8v65-47jx-7mfr
ExploitVendor Advisory