What’s Vulnerable › Vulnerabilities

CVE-2026-23897: Apollo Server is vulnerable to denial of service with `startStandaloneServer`

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-02-04 · updated 2026-06-17
• Weakness: CWE-1333

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 products

• apollographql apollo-server: from 2.0.0 through 3.13.0; from 4.2.0 before 4.13.0; from 5.0.0 before 5.4.0 — fixed in 4.13.0, 5.4.0

How to fix

Upgrade to a fixed version: apollographql apollo-server 4.13.0, 5.4.0. Check the vendor advisory for mitigations.

References

• https://github.com/apollographql/apollo-server/commit/d25a5bdc377826ad424fcf7f8d1d062055911643
• https://github.com/apollographql/apollo-server/commit/e9d49d163a86b8a33be56ed27c494b9acd5400a4
• https://github.com/apollographql/apollo-server/security/advisories/GHSA-mp6q-xf9x-fwf7

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