CVE-2026-23897

Apollo Server is vulnerable to denial of service with `startStandaloneServer`

HIGH
7.5
CVSS Score
Published: February 4, 2026 at 07:18 PM UTC
Updated: June 17, 2026 at 10:22 AM UTC
1 product affected across 1 vendorApollo Server

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Severity
HIGH7.5
Exploit prediction
EPSS 0.7%
SSVC
No known exploit

Description

Apollo Server is an open-source, spec-compliant GraphQL server that's compatible with any GraphQL client, including Apollo Client. In versions from 2.0.0 to 3.13.0, 4.2.0 to before 4.13.0, and 5.0.0 to before 5.4.0, the default configuration of startStandaloneServer from @apollo/server/standalone is vulnerable to denial of service (DoS) attacks through specially crafted request bodies with exotic character set encodings. This issue does not affect users that use @apollo/server as a dependency for integration packages, like @as-integrations/express5 or @as-integrations/next, only direct usage of startStandaloneServer.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v ≤ 3.13.0v < 4.13.0v < 5.4.02.0.0 ≤ v ≤ 3.13.04.2.0 ≤ v < 4.13.05.0.0 ≤ v < 5.4.0
Affected range stops below 4.13.0, so it looks safe — our inference, not a vendor statement
Affected range stops below 5.4.0, so it looks safe — our inference, not a vendor statement

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGHGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-1333

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