CVE-2026-23897Network attack vector

Service interruption via unrestricted request charsets

Published Feb 4, 2026 · Updated Feb 4, 2026

Denial of service in affected Apollo Server releases allows remote attackers to interrupt standalone GraphQL service with crafted HTTP bodies. The startStandaloneServer path passed exotic declared charsets into Express JSON body parsing without an allowlist, triggering inefficient charset processing. Exposure requires direct use of the default standalone server in 2.0.0 through 3.13.0, 4.2.0 through 4.12.x, or 5.0.0 through 5.3.x; framework integrations are not affected.

CVSS severity7.5
High
EPSS probability0.64%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in affected Apollo Server releases allows remote attackers to interrupt standalone GraphQL service with crafted HTTP bodies. The startStandaloneServer path passed exotic declared charsets into Express JSON body parsing without an allowlist, triggering inefficient charset processing. Exposure requires direct use of the default standalone server in 2.0.0 through 3.13.0, 4.2.0 through 4.12.x, or 5.0.0 through 5.3.x; framework integrations are not affected.

The record

CVE
CVE-2026-23897
Published
Feb 4, 2026
Updated
Feb 4, 2026
Vendor
Apollo GraphQL
Product
Apollo Server
Classifications
CWE-1333, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 4, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 4, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 2.0.0, <= 3.13.0
  2. Affected versionversion=>= 4.2.0, < 4.13.0
  3. Affected versionversion=>= 5.0.0, < 5.4.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Apollo GraphQL · Apollo Serverversion=>= 2.0.0, <= 3.13.0; version=>= 4.2.0, < 4.13.0; version=>= 5.0.0, < 5.4.0

Published CVSS scores

7.5GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1333Inefficient Regular Expression Complexity
T1499.003Application Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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