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.
CVE-2026-88351
“—” beside the score: it is equal to the CVSS score beside it.
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.
Also known asEUVD-2026-86022 (ENISA EUVD) · GHSA-cmcq-v328-82vj (GitHub Security Advisories)Source: ENISA EUVD
- CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
An upstream fix is merged but not yet released — mitigate (WAF / firewall / segmentation) until the release ships, then apply it.
- CVSS v3
- 9.8
- EG Score
- 9.8CRITICALmedium confidence
- EG Risk
- 75EG Risk 75/100
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)Severity98% × 45%Impact severity (EG Severity): CVSS 9.8 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.Automatability100% × 15%CISA's SSVC Automatable value: yes (Vulnrichment).SSVC (CISA's decision table, applied by EchelonGraph): Track at low, Track* at medium and Attend at high mission impact.Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (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: An upstream fix is merged but not yet in a tagged release. Until the release ships, restrict network exposure of the affected system or apply the vendor's mitigation on your normal schedule at low or medium mission impact and sooner than that at high, then apply it. - EPSS PROB
- 0.4%
- EPSS %ILE
- 33rd
- 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 (9.8): severity, escalated by confirmed exploitation. This CVE's 9.8 is its impact severity (EG Severity), not escalated.
- EG Severity
- 9.8 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.4% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-01). 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, Track* at medium and Attend at high mission impact.CISA BOD 26-04: 3 days if the affected system is publicly exposed; 60 days if it is not.No released fix is confirmed on this page, but CISA's timeline does not wait for a fix's release: it starts when an agency identifies the flaw on an asset and updates the CDM Agency and Federal Dashboard, and the directive counts patching, decommissioning the system or another action as remediation. Until a fixed release is applied, mitigate as this page's verdict says.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low, Track* at medium and Attend at high mission impact.
An upstream fix is merged but not yet in a tagged release. Until the release ships, restrict network exposure of the affected system or apply the vendor's mitigation on your normal schedule at low or medium mission impact and sooner than that at high, then apply it.
Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (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)3 days if the affected system is publicly exposed; 60 days if it is not.
No released fix is confirmed on this page, but CISA's timeline does not wait for a fix's release: it starts when an agency identifies the flaw on an asset and updates the CDM Agency and Federal Dashboard, and the directive counts patching, decommissioning the system or another action as remediation. Until a fixed release is applied, mitigate as this page's verdict says.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact total (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
September 24, 2026
Last Modified
September 25, 2026
Advisory Details (2)
Auto-updated Oct 31, 2026[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/123commit 3d54d1215bdb (ludocode/mpack)
Fix landed in ludocode/mpack commit 3d54d1215bdb — awaiting tagged release
https://github.com/ludocode/mpack/commit/3d54d1215bdb5478d3ddecaf85884c58b382cd9bVendor 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 21× in last 7d / 138× 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 210 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 110 oldest rows on record are not shown and were not checked, so the counts can still include repeats.
- 2026-11-01 19:35 UTCEG score recompute
- 2026-11-01 19:35 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-11-01 16:35 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-10-31 19:09 UTCEG score recompute
- 2026-10-31 19:09 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-10-30 18:39 UTCEG score recompute
- 2026-10-30 18:39 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-10-29 18:12 UTCEG score recompute
- 2026-10-29 18:12 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-29 16:34 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
- 2026-10-28 17:43 UTCEG score recompute
- 2026-10-28 17:43 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
- 2026-10-27 17:12 UTCEG score recompute
- 2026-10-27 17:12 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
- 2026-10-26 16:44 UTCEG score recompute
- 2026-10-26 16:44 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
- 2026-10-25 16:34 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
- 2026-10-25 16:02 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-25 13:53 UTCEG score recompute
- 2026-10-24 16:34 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
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- 2026-10-24 15:33 UTCEG score recompute
- 2026-10-24 15:33 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-24 11:15 UTCEG score recompute
- 2026-10-24 11:15 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
- 2026-10-23 10:47 UTCEG score recompute
- 2026-10-23 10:47 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
- 2026-10-22 10:17 UTCEG score recompute
- 2026-10-22 10:17 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-21 16:34 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
- 2026-10-21 09:46 UTCEG score recompute
- 2026-10-21 09:46 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
- 2026-10-20 09:20 UTCEG score recompute
- 2026-10-20 09:19 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-19 16:33 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
- 2026-10-19 08:52 UTCEG score recompute
- 2026-10-19 08:52 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-18 16:33 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
- 2026-10-18 08:25 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-18 03:03 UTCEG score recompute
- 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
- 2026-10-17 07:33 UTCEG score recompute
- 2026-10-17 07:32 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-16 16:44 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
- 2026-10-16 07:03 UTCEG score recompute
- 2026-10-16 07:03 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-15 16:33 UTCEPSS rescoreEPSS 0.3% · 21st percentile
- 2026-10-15 05:48 UTCEG score recompute
- 2026-10-15 05:48 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-14 16:34 UTCEPSS rescoreEPSS 0.3% · 21st percentile
- 2026-10-14 01:26 UTCEG score recompute
- 2026-10-14 01:25 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.3% · 21st percentile
- 2026-10-12 21:37 UTCEG score recompute
- 2026-10-12 21:37 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-12 16:35 UTCEPSS rescoreEPSS 0.3% · 21st percentile
- 2026-10-12 14:49 UTCEG score recompute
- 2026-10-12 01:57 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-11 22:10 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-11 19:15 UTCEG score recompute
- 2026-10-11 18:21 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-11 16:32 UTCEG score recompute
- 2026-10-11 13:56 UTCEG score recompute
- 2026-10-11 13:56 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.3% · 21st percentile
- 2026-10-11 13:48 UTCEG score recompute
- 2026-10-11 10:10 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-11 06:24 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-11 02:38 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-10 22:43 UTCEG score recompute
- 2026-10-10 22:43 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.3% · 21st percentile
- 2026-10-10 18:57 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-10 15:09 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-10 11:22 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-10 07:35 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-10 03:43 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-09 23:58 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-09 20:11 UTCEG score recompute
- 2026-10-09 20:11 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.3% · 21st percentile
- 2026-10-09 16:24 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-09 12:38 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-09 08:10 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-09 04:23 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-09 00:37 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-08 20:51 UTCEG score recompute
- 2026-10-08 20:51 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.3% · 21st percentile
- 2026-10-08 17:02 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-08 09:12 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-08 05:25 UTCGHSA enrichmentGHSA-cmcq-v328-82vj · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-08 01:39 UTCEG score recompute
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Frequently asked(5)
What is CVE-2026-88351?
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