CVE-2026-88378

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 — 4 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: 0.4%CVSS: 9.8Exploit: Elevated riskExposed services: Not assessed

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

QuickJS commit 04be24600 contains a heap out-of-bounds write condition in JS_ReadFunctionTag().

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: No fix is confirmed yet. 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, and watch the vendor's advisory for the fix.
EPSS PROB
0.4%
EPSS %ILE
36th
KEV
Not listed

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

No fix is confirmed yet. 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, and watch the vendor's advisory for the fix.

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 29, 2026

Advisory Details (3)

Auto-updated Sep 29, 2026
No patch confirmed yet. Sources: github_pr.
generic

[Bug]Heap-buffer-overflow WRITE in JS_ReadFunctionTag: negative count wraps the allocation size below the header size (CWE-787) · Issue #549 · bellard/quickjs · GitHub

https://github.com/bellard/quickjs/issues/549
github_pr

Reject overflowing integers in bytecode reader

Upstream fix in progress (PR #553 · bellard/quickjs, state=open)

https://github.com/bellard/quickjs/pull/553/changes/42526037cfc0b2a94a875c0de0f4bbeaf597a542
github_pr

Reject overflowing integers in bytecode reader

Upstream fix in progress (PR #553 · bellard/quickjs, state=open)

https://github.com/bellard/quickjs/pull/553

Vendor Advisories for CVE-2026-88378(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 49× in last 7d / 54× 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 13:15 UTCGHSA enrichment
  2. 2026-10-04 09:15 UTCGHSA enrichment
  3. 2026-10-04 05:14 UTCGHSA enrichment
  4. 2026-10-04 01:15 UTCGHSA enrichment
  5. 2026-10-03 21:15 UTCGHSA enrichment
  6. 2026-10-03 17:14 UTCEG score recompute
  7. 2026-10-03 17:14 UTCGHSA enrichment
  8. 2026-10-03 13:13 UTCGHSA enrichment
  9. 2026-10-03 09:12 UTCGHSA enrichment
  10. 2026-10-03 05:10 UTCGHSA enrichment
  11. 2026-10-03 01:10 UTCGHSA enrichment
  12. 2026-10-02 21:10 UTCEG score recompute
  13. 2026-10-02 21:10 UTCGHSA enrichment
  14. 2026-10-02 17:05 UTCGHSA enrichment
  15. 2026-10-02 13:04 UTCGHSA enrichment
  16. 2026-10-02 09:04 UTCGHSA enrichment
  17. 2026-10-02 05:04 UTCGHSA enrichment
  18. 2026-10-02 01:03 UTCGHSA enrichment
  19. 2026-10-01 21:02 UTCEG score recompute
  20. 2026-10-01 21:01 UTCGHSA enrichment
  21. 2026-10-01 19:51 UTCEPSS rescore
  22. 2026-10-01 17:02 UTCGHSA enrichment
  23. 2026-10-01 12:42 UTCGHSA enrichment
  24. 2026-10-01 08:42 UTCGHSA enrichment
  25. 2026-10-01 04:42 UTCGHSA enrichment
Show 29 more
  1. 2026-10-01 00:37 UTCGHSA enrichment
  2. 2026-09-30 20:37 UTCGHSA enrichment
  3. 2026-09-30 16:37 UTCEG score recompute
  4. 2026-09-30 16:37 UTCGHSA enrichment
  5. 2026-09-30 15:04 UTCEPSS rescore
  6. 2026-09-30 12:09 UTCGHSA enrichment
  7. 2026-09-30 08:09 UTCGHSA enrichment
  8. 2026-09-30 04:08 UTCGHSA enrichment
  9. 2026-09-30 00:04 UTCGHSA enrichment
  10. 2026-09-29 19:40 UTCGHSA enrichment
  11. 2026-09-29 15:33 UTCEG score recompute
  12. 2026-09-29 15:33 UTCGHSA enrichment
  13. 2026-09-29 11:33 UTCGHSA enrichment
  14. 2026-09-29 07:32 UTCEG score recompute
  15. 2026-09-29 07:32 UTCGHSA enrichment
  16. 2026-09-29 03:32 UTCEG score recompute
  17. 2026-09-29 03:31 UTCGHSA enrichment
  18. 2026-09-29 02:56 UTCEG score recompute▲ 9.80
  19. 2026-09-29 02:56 UTCGHSA enrichment
  20. 2026-09-29 02:55 UTCMITRE cvelistV5CVSS v3 → 9.8 · severity → CRITICAL
  21. 2026-09-28 13:52 UTCEPSS rescore
  22. 2026-09-27 17:57 UTCEG score recompute
  23. 2026-09-27 17:57 UTCGHSA enrichment
  24. 2026-09-27 13:48 UTCEPSS rescore
  25. 2026-09-26 15:59 UTCEPSS rescore
  26. 2026-09-24 21:16 UTCGHSA enrichment
  27. 2026-09-24 17:33 UTCNVD update
  28. 2026-09-24 16:31 UTCEG score recompute
  29. 2026-09-24 16:26 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-88378?
CVE-2026-88378 is a critical vulnerability published on September 24, 2026. QuickJS commit 04be24600 contains a heap out-of-bounds write condition in JS_ReadFunctionTag().
When was CVE-2026-88378 disclosed?
CVE-2026-88378 was first published on September 24, 2026, with the most recent update on September 29, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-88378 actively exploited?
CVE-2026-88378 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (36th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-88378?
CVE-2026-88378 has a CVSS v3.1 base score of 9.8 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-88378?
No fix for CVE-2026-88378 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-2026-88378 are linked in the Vendor Advisories panel on this page.

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