CVE-2026-19874

CRITICALPre-NVD 9.19.1
EchelonGraph scoreMEDIUM confidence

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

Score 9.1 from GitHub Security Advisory (severity: CRITICAL) published 2026-08-24. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 9.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: CISA-ADP (Vulnrichment) CVSS v3.1, EPSS, GitHub Security Advisory
Trending — 3 sources updated this weekElevated
9.1EG
EchelonGraph verdictPlan mitigationRemediate within your standard update timelines (the SSVC decision on this page).
  • Public exploit or proof-of-concept code is available
CISA-KEV: Not listedEPSS PROB: 0.9%CVSS: 9.1Exploit: Public PoCExposed services: Not assessed

No fix is confirmed yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for the fix.

A heap-based buffer overflow vulnerability exists in Konami's Metal Gear Online 3, originating from improper validation of lobby data fields related to kicked players. The affected function processes a list of kicked player identifiers using the lobby data key "kick_num" to determine the number of entries, and individual kicked player IDs supplied via keys in the format "kicked_id_%i". The function does not validate that "kick_num" falls within the expected bounds. The game design limits matches to a maximum of 16 players, and the corresponding buffer for storing kicked player IDs is sized accordingly. If "kick_num" exceeds this limit, the function continues writing the provided player IDs past the end of the intended buffer and into adjacent memory regions. These adjacent regions contain Steam callback handler structures responsible for processing lobby data updates, lobby messages, and other related events. By supplying an oversized "kick_num" value and appropriate "kicked_id_%i" fields, an attacker can overwrite fields within the callback handler structures, including function pointers and callback argument values. Successful exploitation may enable control-flow hijacking, potentially allowing arbitrary code execution within the game process.

CVSS v3
9.1
EG Score
9.1CRITICALmedium confidence
EG Risk
57
EG Risk 57/100

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.
Exploitation40% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at every mission impact level.
Exploitation none (CISA Vulnrichment) · Automatable no (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: No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines, and watch the vendor's advisory for the fix.
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.GitHub Security Advisory CVSS
EG Likelihood
0.9% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-19). 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 every mission impact level.CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade 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 every mission impact level.

No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines, and watch the vendor's advisory for the fix.

Exploitation none (CISA Vulnrichment) · Automatable no (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)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable no (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

August 24, 2026

Last Modified

October 12, 2026

Advisory Details (3)

Auto-updated Sep 15, 2026
No fix on record yet. Sources: cert.
CERT

VU#728712 - Konami's Metal Gear Online 3 contains a heap-based buffer overflow

https://www.kb.cert.org/vuls/id/728712
CERT

VU#728712 - Konami's Metal Gear Online 3 contains a heap-based buffer overflow

https://kb.cert.org/vuls/id/728712
Web page

CWE - CWE-122: Heap-based Buffer Overflow (4.20)

https://cwe.mitre.org/data/definitions/122.html

Vendor Advisories for CVE-2026-19874(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 19× in last 7d / 143× 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 100 of 341 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. None are among the latest 100 rows. The 241 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-20 16:32 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  2. 2026-10-20 04:06 UTCEG score recompute
  3. 2026-10-20 04:06 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  4. 2026-10-19 16:31 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  5. 2026-10-19 03:19 UTCEG score recompute
  6. 2026-10-19 03:18 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  7. 2026-10-18 03:57 UTCEG score recompute
  8. 2026-10-18 02:33 UTCEG score recompute
  9. 2026-10-18 02:33 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  10. 2026-10-17 16:33 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  11. 2026-10-17 01:48 UTCEG score recompute
  12. 2026-10-17 01:48 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  13. 2026-10-16 16:41 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  14. 2026-10-16 01:02 UTCEG score recompute
  15. 2026-10-16 01:02 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  16. 2026-10-15 16:31 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  17. 2026-10-14 20:01 UTCEG score recompute
  18. 2026-10-14 20:00 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  19. 2026-10-14 16:32 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  20. 2026-10-13 16:33 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  21. 2026-10-13 16:11 UTCEG score recompute
  22. 2026-10-13 16:11 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  23. 2026-10-12 16:33 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  24. 2026-10-12 15:25 UTCEG score recompute
  25. 2026-10-12 15:25 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
Show 75 more
  1. 2026-10-12 09:25 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  2. 2026-10-11 20:06 UTCEG score recompute
  3. 2026-10-11 17:19 UTCEG score recompute
  4. 2026-10-11 14:51 UTCEG score recompute
  5. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  6. 2026-10-10 19:59 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  7. 2026-10-10 12:39 UTCEG score recompute
  8. 2026-10-10 12:39 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  9. 2026-10-09 20:06 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  10. 2026-10-09 04:53 UTCEG score recompute
  11. 2026-10-09 04:53 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  12. 2026-10-08 17:11 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  13. 2026-10-08 08:18 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  14. 2026-10-08 04:01 UTCEG score recompute
  15. 2026-10-08 04:01 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  16. 2026-10-07 23:47 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  17. 2026-10-07 10:13 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  18. 2026-10-07 05:55 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  19. 2026-10-07 01:37 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  20. 2026-10-06 21:15 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  21. 2026-10-06 16:40 UTCEG score recompute
  22. 2026-10-06 16:40 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  23. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  24. 2026-10-06 12:05 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  25. 2026-10-06 07:45 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  26. 2026-10-06 02:51 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  27. 2026-10-05 18:38 UTCEG score recompute
  28. 2026-10-05 18:38 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  29. 2026-10-05 17:42 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  30. 2026-10-05 14:21 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  31. 2026-10-05 10:03 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  32. 2026-10-05 05:45 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  33. 2026-10-05 01:27 UTCEG score recompute
  34. 2026-10-05 01:27 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  35. 2026-10-04 23:21 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  36. 2026-10-04 20:42 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  37. 2026-10-04 15:36 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  38. 2026-10-04 11:08 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  39. 2026-10-04 06:37 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  40. 2026-10-04 02:19 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  41. 2026-10-03 20:50 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  42. 2026-10-03 16:32 UTCEG score recompute
  43. 2026-10-03 16:32 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  44. 2026-10-03 05:03 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  45. 2026-10-03 00:37 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  46. 2026-10-02 19:55 UTCEG score recompute
  47. 2026-10-02 19:55 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  48. 2026-10-02 15:37 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  49. 2026-10-02 11:03 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  50. 2026-10-02 06:43 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  51. 2026-10-02 01:21 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  52. 2026-10-01 21:03 UTCEG score recompute
  53. 2026-10-01 21:03 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  54. 2026-10-01 19:49 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  55. 2026-10-01 14:14 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  56. 2026-10-01 09:55 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  57. 2026-10-01 05:37 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  58. 2026-10-01 01:08 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  59. 2026-09-30 20:18 UTCEG score recompute
  60. 2026-09-30 20:18 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  61. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  62. 2026-09-30 11:45 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  63. 2026-09-30 07:13 UTCEG score recompute
  64. 2026-09-30 07:13 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  65. 2026-09-29 15:20 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  66. 2026-09-29 15:14 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  67. 2026-09-29 06:09 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  68. 2026-09-29 01:51 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  69. 2026-09-28 21:32 UTCEG score recompute
  70. 2026-09-28 21:32 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  71. 2026-09-28 16:26 UTCEG score recompute
  72. 2026-09-28 16:26 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  73. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  74. 2026-09-28 12:02 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1
  75. 2026-09-28 07:43 UTCGHSA enrichmentGHSA-ggf5-p56j-ccc2 · GitHub severity CRITICAL · GitHub CVSS 9.1

Publicly available exploits

(1 reference)

Public exploit code is referenced for this CVE (1 GitHub PoC). No fix is confirmed yet, so defenders should restrict or isolate affected systems accordingly until one is published.

  • GitHub PoCalicealys/mgo3-rce
    Published Jul 8, 2026

    CVE-2026-19874

    Open source ↗

Frequently asked(5)

What is CVE-2026-19874?
CVE-2026-19874 is a critical-severity vulnerability; its CVE record was published on August 24, 2026. A heap-based buffer overflow vulnerability exists in Konami's Metal Gear Online 3, originating from improper validation of lobby data fields related to kicked players. The affected function processes a list of kicked player identifiers using the lobby data key "kicknum" to determine the number of…
When was the CVE record for CVE-2026-19874 published?
The CVE record for CVE-2026-19874 was published on August 24, 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 12, 2026; the record at its source may have been updated since.
Is CVE-2026-19874 actively exploited?
CVE-2026-19874 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-2026-19874?
CVE-2026-19874 has a CVSS v3.1 base score of 9.1 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-19874?
No fix for CVE-2026-19874 is confirmed yet. Until one is published, restrict network exposure of the affected system or apply the vendor's mitigation — for example, keep it off the internet or limit it to trusted networks — and watch the vendor's advisory for the fix. The vendor advisories EchelonGraph has for CVE-2026-19874 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2026-19874

Explore →

Is Your Infrastructure Affected by CVE-2026-19874?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.