What is CVE-2026-21859?

CVE-2026-21859 is a medium-severity vulnerability in Axllent Mailpit, classified under Server-Side Request Forgery (SSRF). CVSS score: 5.8/10. Published 2026-01-08.

How severe is CVE-2026-21859?

Medium severity. CVSS v3 base score is 5.8 out of 10.

SSRF in Axllent Mailpit

CVE-2026-21859

Mailpit is an email testing tool and API for developers. Versions 1.28.0 and below have a Server-Side Request Forgery (SSRF) vulnerability in the /proxy endpoint, allowing attackers to make requests to internal network resources. The /prox…

Vulnerability class: SSRF (Server-Side Request Forgery)

EPSS: 0.008 (51.0th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.8 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N.

Affected products

Axllent Mailpit — versions < 1.28.1

Weakness classification (CWE)

CWE-918 — Server-Side Request Forgery (SSRF)

References

security-advisories@github.com (x_refsource_CONFIRM, Exploit, Vendor Advisory)
security-advisories@github.com (Patch, x_refsource_MISC)

Frequently asked questions

What is CVE-2026-21859?: CVE-2026-21859 is a medium-severity vulnerability in Axllent Mailpit, classified under Server-Side Request Forgery (SSRF). CVSS score: 5.8/10. Published 2026-01-08.
How severe is CVE-2026-21859?: Medium severity. CVSS v3 base score is 5.8 out of 10.