CVE-2026-88351

CRITICALPre-NVD 9.89.8—
EchelonGraph scoreHIGH confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-09-24. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cisa-adp, epss, ghsa
Trending — 3 sources updated this weekElevated
9.8EG
EchelonGraph verdictPlan mitigationSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 9.8Exploit: Elevated riskExposed services: Not assessed

An upstream fix is merged but not yet released — mitigate (WAF / firewall / segmentation) until the release ships, then apply it.

An integer overflow vulnerability exists in the MPack Node API in MPack 1.1.1 on 32-bit platforms. When parsing a specially crafted MessagePack array32 or map32 object with an excessively large element count, the page allocation size calculation in mpack_tree_parse_children() can overflow size_t and produce an undersized allocation. Subsequent parsing writes mpack_node_data_t records beyond the allocated heap buffer, resulting in heap-buffer-overflow, memory corruption, and denial of service.

CVSS v3
9.8
EG Score
9.8CRITICALhigh confidence
EG Risk
75
EG Risk 75/100CISA SSVC

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity98% × 45%
Exploitation40% × 40%
Automatability100% × 15%
CISA SSVC: Track at low, Track* at medium and Attend at high mission impact.
Action: An upstream fix is merged but not yet in a tagged release. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high until it ships, then apply the release.
EPSS PROB
0.3%
EPSS %ILE
21st
KEV
Not listed

CISA SSVCTrack at low, Track* at medium and Attend at high mission impact.

An upstream fix is merged but not yet in a tagged release. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high until it ships, then apply the release.

Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

September 24, 2026

Last Modified

September 25, 2026

Advisory Details (2)

Auto-updated Oct 2, 2026
Upstream fix merged — awaiting tagged release. Sources: github_commit.
generic

[Bug]Heap-buffer-overflow via integer overflow in page allocation (sizeof(mpack_node_data_t) * (total-1)) when parsing huge array32/map32 in MPack Node API (32-bit platforms) · Issue #123 · ludocode/mpack · GitHub

https://github.com/ludocode/mpack/issues/123
github_commit

commit 3d54d1215bdb (ludocode/mpack)

Fix landed in ludocode/mpack commit 3d54d1215bdb — awaiting tagged release

https://github.com/ludocode/mpack/commit/3d54d1215bdb5478d3ddecaf85884c58b382cd9b

Vendor Advisories for CVE-2026-88351(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 57× in last 7d / 80× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. 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. Most recent first.

  1. 2026-10-04 10:34 UTCGHSA enrichment
  2. 2026-10-04 06:43 UTCGHSA enrichment
  3. 2026-10-04 02:57 UTCGHSA enrichment
  4. 2026-10-03 23:11 UTCGHSA enrichment
  5. 2026-10-03 19:18 UTCGHSA enrichment
  6. 2026-10-03 15:32 UTCEG score recompute
  7. 2026-10-03 15:32 UTCGHSA enrichment
  8. 2026-10-03 11:44 UTCGHSA enrichment
  9. 2026-10-03 07:32 UTCGHSA enrichment
  10. 2026-10-03 03:42 UTCGHSA enrichment
  11. 2026-10-02 23:52 UTCGHSA enrichment
  12. 2026-10-02 20:05 UTCEG score recompute
  13. 2026-10-02 20:05 UTCGHSA enrichment
  14. 2026-10-02 16:15 UTCGHSA enrichment
  15. 2026-10-02 16:15 UTCGHSA enrichment
  16. 2026-10-02 16:15 UTCGHSA enrichment
  17. 2026-10-02 12:27 UTCGHSA enrichment
  18. 2026-10-02 08:42 UTCGHSA enrichment
  19. 2026-10-02 04:56 UTCGHSA enrichment
  20. 2026-10-02 01:07 UTCGHSA enrichment
  21. 2026-10-01 21:19 UTCEG score recompute
  22. 2026-10-01 21:19 UTCGHSA enrichment
  23. 2026-10-01 19:51 UTCEPSS rescore
  24. 2026-10-01 17:31 UTCGHSA enrichment
  25. 2026-10-01 13:45 UTCGHSA enrichment
Show 55 more
  1. 2026-10-01 09:59 UTCGHSA enrichment
  2. 2026-10-01 06:13 UTCGHSA enrichment
  3. 2026-10-01 02:27 UTCGHSA enrichment
  4. 2026-09-30 22:41 UTCGHSA enrichment
  5. 2026-09-30 18:55 UTCGHSA enrichment
  6. 2026-09-30 15:09 UTCEG score recompute
  7. 2026-09-30 15:09 UTCGHSA enrichment
  8. 2026-09-30 15:04 UTCEPSS rescore
  9. 2026-09-30 11:23 UTCGHSA enrichment
  10. 2026-09-30 07:37 UTCGHSA enrichment
  11. 2026-09-30 03:50 UTCGHSA enrichment
  12. 2026-09-30 00:04 UTCGHSA enrichment
  13. 2026-09-29 18:16 UTCEG score recompute
  14. 2026-09-29 18:16 UTCGHSA enrichment
  15. 2026-09-29 13:45 UTCGHSA enrichment
  16. 2026-09-29 09:58 UTCGHSA enrichment
  17. 2026-09-29 06:11 UTCGHSA enrichment
  18. 2026-09-29 02:26 UTCGHSA enrichment
  19. 2026-09-28 22:40 UTCEG score recompute
  20. 2026-09-28 22:40 UTCGHSA enrichment
  21. 2026-09-28 18:54 UTCGHSA enrichment
  22. 2026-09-28 15:08 UTCEG score recompute
  23. 2026-09-28 15:08 UTCGHSA enrichment
  24. 2026-09-28 13:52 UTCEPSS rescore
  25. 2026-09-28 11:21 UTCGHSA enrichment
  26. 2026-09-28 07:35 UTCGHSA enrichment
  27. 2026-09-28 03:49 UTCGHSA enrichment
  28. 2026-09-28 00:01 UTCGHSA enrichment
  29. 2026-09-27 20:15 UTCGHSA enrichment
  30. 2026-09-27 16:28 UTCEG score recompute
  31. 2026-09-27 16:28 UTCGHSA enrichment
  32. 2026-09-27 13:48 UTCEPSS rescore
  33. 2026-09-27 12:42 UTCGHSA enrichment
  34. 2026-09-27 08:56 UTCGHSA enrichment
  35. 2026-09-27 05:09 UTCGHSA enrichment
  36. 2026-09-27 01:21 UTCGHSA enrichment
  37. 2026-09-26 21:35 UTCGHSA enrichment
  38. 2026-09-26 17:49 UTCEG score recompute
  39. 2026-09-26 17:48 UTCGHSA enrichment
  40. 2026-09-26 15:59 UTCEPSS rescore
  41. 2026-09-26 13:59 UTCGHSA enrichment
  42. 2026-09-26 09:53 UTCGHSA enrichment
  43. 2026-09-26 06:05 UTCGHSA enrichment
  44. 2026-09-26 02:18 UTCEG score recompute
  45. 2026-09-26 02:18 UTCGHSA enrichment
  46. 2026-09-25 22:28 UTCGHSA enrichment
  47. 2026-09-25 18:40 UTCEG score recompute
  48. 2026-09-25 18:40 UTCGHSA enrichment
  49. 2026-09-25 18:15 UTCEG score recompute▲ 9.80
  50. 2026-09-25 18:15 UTCGHSA enrichment
  51. 2026-09-25 18:14 UTCMITRE cvelistV5CVSS v3 → 9.8 · severity → CRITICAL
  52. 2026-09-24 21:16 UTCGHSA enrichment
  53. 2026-09-24 15:28 UTCNVD update
  54. 2026-09-24 14:48 UTCEG score recompute
  55. 2026-09-24 14:47 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-88351?
CVE-2026-88351 is a critical vulnerability published on September 24, 2026. An integer overflow vulnerability exists in the MPack Node API in MPack 1.1.1 on 32-bit platforms. When parsing a specially crafted MessagePack array32 or map32 object with an excessively large element count, the page allocation size calculation in mpacktreeparsechildren() can overflow sizet and…
When was CVE-2026-88351 disclosed?
CVE-2026-88351 was first published on September 24, 2026, with the most recent update on September 25, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-88351 actively exploited?
CVE-2026-88351 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (21st percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-88351?
CVE-2026-88351 has a CVSS v3.1 base score of 9.8 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-88351?
An upstream fix for CVE-2026-88351 has been merged but is not yet in a tagged release. Until it ships, restrict network exposure of the affected system or apply the vendor's mitigation, then update to the release that contains the fix. The vendor advisories EchelonGraph has for CVE-2026-88351 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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