Appsmith: SSRF via `POST /api/v1/admin/send-test-email` — JavaMail Bypasses WebClient IP Filter

published 2026-06-24 4 mo ago modified 2026-10-25 14 d ago also EUVD-2026-39129

cvss: 2.7; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 30%
public exploits: 0; none known

Appsmith is a platform to build admin panels, internal tools, and dashboards. Prior to 1.99, the POST /api/v1/admin/send-test-email endpoint accepts attacker-controlled smtpHost and smtpPort values and establishes a raw JavaMail TCP connection without any IP validation. This completely bypasses WebClientUtils.IP_CHECK_FILTER, which only applies to Spring WebClient HTTP requests. Additionally, the raw MailException.getMessage() is returned verbatim in the API error response, enabling error-based internal port scanning and service banner enumeration. This vulnerability is fixed in 1.99.

Patch / fix

fixed in 1

appsmith appsmith 1.99

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 4 mo ago (2026-06-26)

Exploit prediction

0.37% chance of exploitation in the next 30 days, higher than 30% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/appsmithorg/appsmith/security/advisories/GHSA-vvxf-f8q9-86gh referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	4.0	5.1	CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N
CNA	4.0	5.1	CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD	3.1	2.7	CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:N

Affected products

appsmithorg appsmith

Classification

Weakness

CWE-209 Generation of Error Message Containing Sensitive Information
CWE-918 Server-Side Request Forgery

References

github.com /appsmithorg/appsmith/security/advisories/GHSA-vvxf-f8q9-86gh
exploit, third-party-advisory

Sources

CVE List CVE-2026-49979
NVD CVE-2026-49979

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.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.

Summary