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

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.

Published: 2026-02-04 Last update: 2026-03-18 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-23897 is rated Low Risk (36.1/100): CVSS High severity, with low exploitation likelihood (EPSS 0.05%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-23897

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-08 0.02% 0.05% +0.03%
2 2026-03-21 0.06% 0.02% -0.03%
3 2026-02-10 — 0.06% —

Full EPSS history (4 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-23897

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]

Weakness enumeration for CVE-2026-23897

GitHub Security Advisory for CVE-2026-23897

GHSA-mp6q-xf9x-fwf7 · Severity: high · Ecosystem: npm — Apollo Serve vulnerable to Denial of Service with `startStandaloneServer`

Affected software / configurations for CVE-2026-23897

Vendor Product Version Raw CPE
apollographql apollo_server >= 2.0.0, <= 3.13.0 cpe:2.3:a:apollographql:apollo_server:*:*:*:*:*:*:*:*
apollographql apollo_server >= 4.2.0, < 4.13.0 cpe:2.3:a:apollographql:apollo_server:*:*:*:*:*:*:*:*
apollographql apollo_server >= 5.0.0, < 5.4.0 cpe:2.3:a:apollographql:apollo_server:*:*:*:*:*:*:*:*

References for CVE-2026-23897

cvelogic Threat Intelligence