CVE-2026-40324

CRITICALNVD 9.19.1
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to NVD's CVSS score.

This critical-severity CVE scores 9.1 under NVD CVSS v3. EPSS exploit probability: 0.9% (59th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from NVD CVSS v3
Sources: EPSS, NVD CVSS v3

Also known asEUVD-2026-23579 (ENISA EUVD)Source: ENISA EUVD

9.1EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.9%CVSS: 9.1Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

Hot Chocolate is an open-source GraphQL server. Prior to versions 12.22.7, 13.9.16, 14.3.1, and 15.1.14, Hot Chocolate's recursive descent parser Utf8GraphQLParser has no recursion depth limit. A crafted GraphQL document with deeply nested selection sets, object values, list values, or list types can trigger a StackOverflowException on payloads as small as 40 KB. Because StackOverflowException is uncatchable in .NET (since .NET 2.0), the entire worker process is terminated immediately. All in-flight HTTP requests, background IHostedService tasks, and open WebSocket subscriptions on that worker are dropped. The orchestrator (Kubernetes, IIS, etc.) must restart the process. This occurs before any validation rules run — MaxExecutionDepth, complexity analyzers, persisted query allow-lists, and custom IDocumentValidatorRule implementations cannot intercept the crash because Utf8GraphQLParser.Parse is invoked before validation. The MaxAllowedFields=2048 limit does not help because the crashing payloads contain very few fields. The fix in versions 12.22.7, 13.9.16, 14.3.1, and 15.1.14 adds a MaxAllowedRecursionDepth option to ParserOptions with a safe default, and enforces it across all recursive parser methods (ParseSelectionSet, ParseValueLiteral, ParseObject, ParseList, ParseTypeReference, etc.). When the limit is exceeded, a catchable SyntaxException is thrown instead of overflowing the stack. There is no application-level workaround. StackOverflowException cannot be caught in .NET. The only mitigation is to upgrade to a patched version. Operators can reduce (but not eliminate) risk by limiting HTTP request body size at the reverse proxy or load balancer layer, though the smallest crashing payload (40 KB) is well below most default body size limits and is highly compressible (~few hundred bytes via gzip).

CVSS v3
9.1
EG Score
9.1CRITICALmedium confidence
EG Risk
56
EG Risk 56/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity91% × 45%
Impact severity (EG Severity): CVSS 9.1 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.9% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.9%
EPSS %ILE
59th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (9.1): severity, escalated by confirmed exploitation. This CVE's 9.1 is its impact severity (EG Severity), not escalated.

EG Severity
9.1 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.NVD CVSS v3 · CVSS v3.0 or v3.1
EG Likelihood
0.9% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-29). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; 60 days if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

April 18, 2026

Last Modified

October 26, 2026

Advisory Details (10)

Auto-updated Aug 1, 2026
Patch available. Sources: github_commit, github_pr, github_release.
GitHub release Patch Available

14.3.1

Patch available: ChilliCream/graphql-platform 14.3.1

https://github.com/ChilliCream/graphql-platform/releases/tag/14.3.1
GitHub release Patch Available

13.9.16

Patch available: ChilliCream/graphql-platform 13.9.16

https://github.com/ChilliCream/graphql-platform/releases/tag/13.9.16
GitHub release Patch Available

12.22.7

Patch available: ChilliCream/graphql-platform 12.22.7

https://github.com/ChilliCream/graphql-platform/releases/tag/12.22.7
GitHub pull request

Add depth limit to GraphQL parser

Fix merged in ChilliCream/graphql-platform PR #9531 on 2026-04-10 — awaiting tagged release

https://github.com/ChilliCream/graphql-platform/pull/9531
GitHub pull request

Add depth limit to GraphQL parser

Fix merged in ChilliCream/graphql-platform PR #9530 on 2026-04-10 — awaiting tagged release

https://github.com/ChilliCream/graphql-platform/pull/9530
GitHub pull request

Add depth limit to GraphQL parser

Fix merged in ChilliCream/graphql-platform PR #9528 on 2026-04-10 — awaiting tagged release

https://github.com/ChilliCream/graphql-platform/pull/9528
GitHub commit

commit b9271e6a5004 (ChilliCream/graphql-platform)

Fix landed in ChilliCream/graphql-platform commit b9271e6a5004 — awaiting tagged release

https://github.com/ChilliCream/graphql-platform/commit/b9271e6a500484c002fd528dcd34d1a9b445480f
GitHub commit

commit b185eb276c9e (ChilliCream/graphql-platform)

Fix landed in ChilliCream/graphql-platform commit b185eb276c9e — awaiting tagged release

https://github.com/ChilliCream/graphql-platform/commit/b185eb276c9ee227bd44616ff113be7f01a66c69
GitHub commit

commit 4cbaf67d366f (ChilliCream/graphql-platform)

Fix landed in ChilliCream/graphql-platform commit 4cbaf67d366f — awaiting tagged release

https://github.com/ChilliCream/graphql-platform/commit/4cbaf67d366f800fc1e484bc5c06dfcf27b45023
GitHub commit

commit 08c0caa42ca3 (ChilliCream/graphql-platform)

Fix landed in ChilliCream/graphql-platform commit 08c0caa42ca3 — awaiting tagged release

https://github.com/ChilliCream/graphql-platform/commit/08c0caa42ca33c121bbed49d2db892e5bf6fb541

Affected Packages

(1 across 1 ecosystem)
NuGet(1)
PackageVulnerable rangeFix by version rangeDependents
HotChocolate.Language15.0.0 ... 15.1.9 (18 versions)
  • every version up to 12.22.7: fixed in 12.22.7
  • 13.0.0 up to 13.9.16: fixed in 13.9.16
  • 14.0.0 up to 14.3.1: fixed in 14.3.1
  • 15.0.0 up to 15.1.14: fixed in 15.1.14
—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 15× in last 7d / 52× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 99 of 217 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 1 repeat row among the latest 100 is merged into the row it repeats. The 118 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-29 21:28 UTCEG score recompute
  2. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  3. 2026-10-28 21:48 UTCEG score recompute
  4. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  5. 2026-10-27 22:11 UTCEG score recompute
  6. 2026-10-27 16:31 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  7. 2026-10-26 22:27 UTCEG score recompute
  8. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  9. 2026-10-26 13:22 UTCEG score recompute
  10. 2026-10-25 16:32 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  11. 2026-10-25 14:31 UTCEG score recompute
  12. 2026-10-25 13:33 UTCEG score recompute
  13. 2026-10-24 16:32 UTCEPSS rescoreEPSS 1.0% · 63rd percentile
  14. 2026-10-24 13:53 UTCEG score recompute
  15. 2026-10-23 16:31 UTCEPSS rescoreEPSS 1.0% · 63rd percentile
  16. 2026-10-23 14:15 UTCEG score recompute
  17. 2026-10-22 16:34 UTCEPSS rescoreEPSS 1.0% · 63rd percentile
  18. 2026-10-22 14:36 UTCEG score recompute
  19. 2026-10-21 16:33 UTCEPSS rescoreEPSS 1.0% · 63rd percentile
  20. 2026-10-21 14:38 UTCEG score recompute
  21. 2026-10-20 16:33 UTCEPSS rescoreEPSS 1.0% · 63rd percentile
  22. 2026-10-20 14:49 UTCEG score recompute
  23. 2026-10-19 16:32 UTCEPSS rescoreEPSS 1.0% · 63rd percentile
  24. 2026-10-19 14:10 UTCEG score recompute
  25. 2026-10-18 16:32 UTCEPSS rescoreEPSS 1.0% · 63rd percentile
Show 74 more
  1. 2026-10-18 03:43 UTCEG score recompute
  2. 2026-10-17 16:34 UTCEPSS rescoreEPSS 1.0% · 63rd percentile
  3. 2026-10-17 14:51 UTCEG score recompute
  4. 2026-10-16 16:42 UTCEPSS rescoreEPSS 1.0% · 63rd percentile
  5. 2026-10-16 15:12 UTCEG score recompute
  6. 2026-10-15 16:32 UTCEPSS rescoreEPSS 1.0% · 63rd percentile
  7. 2026-10-15 15:34 UTCEG score recompute
  8. 2026-10-14 16:33 UTCEPSS rescoreEPSS 1.0% · 63rd percentile
  9. 2026-10-14 09:51 UTCEG score recompute
  10. 2026-10-13 16:34 UTCEPSS rescoreEPSS 1.0% · 63rd percentile
  11. 2026-10-13 07:46 UTCEG score recompute
  12. 2026-10-12 16:34 UTCEPSS rescoreEPSS 1.0% · 63rd percentile
  13. 2026-10-12 16:09 UTCEG score recompute
  14. 2026-10-11 19:51 UTCEG score recompute
  15. 2026-10-11 17:05 UTCEG score recompute
  16. 2026-10-11 14:31 UTCEG score recompute
  17. 2026-10-11 13:48 UTCEPSS rescoreEPSS 1.0% · 63rd percentile
  18. 2026-10-11 06:55 UTCOSV refresh
  19. 2026-10-10 20:00 UTCEPSS rescoreEPSS 1.0% · 63rd percentile
  20. 2026-10-09 20:07 UTCEPSS rescoreEPSS 1.0% · 63rd percentile
  21. 2026-10-08 17:12 UTCEPSS rescoreEPSS 1.0% · 63rd percentile
  22. 2026-10-07 23:48 UTCEPSS rescoreEPSS 1.0% · 63rd percentile
  23. 2026-10-06 15:17 UTCEPSS rescoreEPSS 1.0% · 63rd percentile
  24. 2026-10-05 17:43 UTCEPSS rescoreEPSS 1.0% · 63rd percentile
  25. 2026-10-04 23:22 UTCEPSS rescoreEPSS 1.0% · 63rd percentile
  26. 2026-10-03 14:25 UTCEPSS rescoreEPSS 1.0% · 63rd percentile
  27. 2026-10-01 19:50 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  28. 2026-09-30 15:03 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  29. 2026-09-27 13:48 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  30. 2026-09-26 15:58 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  31. 2026-09-26 00:26 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  32. 2026-09-21 19:49 UTCOSV refresh
  33. 2026-09-20 20:15 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  34. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  35. 2026-09-17 19:30 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  36. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  37. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  38. 2026-09-15 03:11 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  39. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  40. 2026-09-12 15:01 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  41. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  42. 2026-09-11 09:37 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  43. 2026-09-10 09:34 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  44. 2026-09-08 22:00 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  45. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  46. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  47. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  48. 2026-09-02 16:08 UTCOSV refresh
  49. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  50. 2026-09-01 13:53 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  51. 2026-09-01 04:39 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  52. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  53. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.9% · 56th percentile
  54. 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.9% · 56th percentile
  55. 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  56. 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  57. 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  58. 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  59. 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  60. 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.9% · 56th percentile
  61. 2026-08-19 17:03 UTCEPSS rescoreEPSS 0.9% · 56th percentile
  62. 2026-08-18 13:48 UTCEPSS rescoreEPSS 0.9% · 56th percentile
  63. 2026-08-17 13:47 UTCEPSS rescoreEPSS 0.9% · 56th percentile
  64. 2026-08-16 14:56 UTCEPSS rescoreEPSS 0.9% · 56th percentile
  65. 2026-08-16 06:28 UTCEG score recompute
  66. 2026-08-16 02:14 UTCEPSS rescoreEPSS 0.9% · 56th percentile
  67. 2026-08-15 01:30 UTCEPSS rescoreEPSS 0.9% · 56th percentile
  68. 2026-08-14 04:36 UTCEG score recompute
  69. 2026-08-13 22:00 UTCEPSS rescoreEPSS 0.9% · 56th percentile
  70. 2026-08-12 18:47 UTCEG score recompute
  71. 2026-08-12 13:51 UTCEPSS rescoreEPSS 0.9% · 56th percentile
  72. 2026-08-11 16:57 UTCEG score recompute
  73. 2026-08-11 13:43 UTCEPSS rescoreEPSS 0.9% · 56th percentile
  74. 2026-08-11 02:32 UTCEG score recompute

Frequently asked(5)

What is CVE-2026-40324?
CVE-2026-40324 is a critical-severity vulnerability; its CVE record was published on April 18, 2026. Hot Chocolate is an open-source GraphQL server. Prior to versions 12.22.7, 13.9.16, 14.3.1, and 15.1.14, Hot Chocolate's recursive descent parser Utf8GraphQLParser has no recursion depth limit. A crafted GraphQL document with deeply nested selection sets, object values, list values, or list types…
When was the CVE record for CVE-2026-40324 published?
The CVE record for CVE-2026-40324 was published on April 18, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of October 26, 2026; the record at its source may have been updated since.
Is CVE-2026-40324 actively exploited?
CVE-2026-40324 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.9% probability of exploitation in the next 30 days (59th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-40324?
CVE-2026-40324 has a CVSS v3 base score of 9.1 (NVD).
How do I remediate CVE-2026-40324?
A fix for CVE-2026-40324 is available: update to the fixed version the vendor names in its advisory.

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