Is CVE-2026-55455 in the CISA KEV catalog?

No. CVE-2026-55455 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-55455?

CVE-2026-55455 has a CVSS v3 base score of 9.1 (CRITICAL).

What is the EPSS score for CVE-2026-55455?

CVE-2026-55455 has an EPSS score of 0.22% (12th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-55455?

Upgrade appsmith to 2.1 or later.

CVE & CISA-KEV Catalog

CVE-2026-55455

CRITICAL

9.1

CVSS v3

NVD

Description

Appsmith is a platform to build admin panels, internal tools, and dashboards. Prior to 2.1, the outbound HTTP host filter applied by WebClientUtils (used by the REST API and GraphQL datasource plugins) validates hosts against an exact-match string denylist. The comprehensive address-class check (loopback, any-local, link-local, fc00::/7) exists only on a separate code path used by SMTP, not by the HTTP plugin path. As a result, an authenticated user can craft outbound requests that reach loopback-bound services inside the container. This vulnerability is fixed in 2.1.

CWE-918Server-Side Request Forgery (SSRF)

How to fix

Remediation Available

appsmithNVD

Affected:< 2.1Fixed in:2.1CVE-2026-55455derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityNone

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

Exploit Intelligence

0.22%probability of exploitation in 30 days

12thpercentile

Low risk: more likely to be exploited than 12% of all known CVEs.

References

Third-Party Advisory1

github.com

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-06-26.