CVE-2026-55455: Appsmith is a platform to build admin panels, internal tools, and dashboards

Q: How do I fix CVE-2026-55455?

appsmith: upgrade to 2.1. Exact commands for each OS are on this page.

Q: Is CVE-2026-55455 being exploited?

CVE-2026-55455 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-55455 affect?

CVE-2026-55455 affects appsmith. Severity is critical (CVSS 9.1). 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

Q: How urgent is CVE-2026-55455?

Priority 45/100. Critical severity; Remotely exploitable, no login, no user action

This month

CRITICAL 9.1REMOTEUPGRADE

CVE-2026-55455 is a critical-severity flaw (CVSS 9.1) affecting appsmith. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 u

Why this priority

Critical severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.1 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 67%)
CISA exploited list	No
Weakness	CWE-918
Published	2026-06-24
Last modified	2026-10-25

Publisher (CNA): GitHub, Inc. · Vendor: appsmith

Last updated 2026-10-25 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-06-24 22:16 UTCPublished CVE record published
2026-10-25 23:10 UTCUpdated Record last modified

appsmith appsmith UPGRADE

Affected: < 2.1

Fixed in: 2.1

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy appsmith || rpm -q appsmith || appsmith --version

2. UPGRADE to 2.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade appsmith

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade appsmith

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-55455?

appsmith: upgrade to 2.1. Exact commands for each OS are on this page.

Is CVE-2026-55455 being exploited?

CVE-2026-55455 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-55455 affect?

CVE-2026-55455 affects appsmith. Severity is critical (CVSS 9.1). 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

How urgent is CVE-2026-55455?

Priority 45/100. Critical severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-55454 CRITICAL 9.9 UPGRADE Appsmith is a platform to build admin panels, internal tools, and dashboards
CVE-2026-50189 HIGH 7.2 UPGRADE Appsmith is a platform to build admin panels, internal tools, and dashboards
CVE-2026-49979 LOW 2.7 UPGRADE Appsmith is a platform to build admin panels, internal tools, and dashboards

References

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