CVE-2026-100660

HIGHPre-NVD 7.57.5—
EchelonGraph scoreHIGH confidence

Score 7.5 from GitHub Security Advisory (severity: HIGH) published 2026-09-26. A secondary CVSS source baseline 7.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this weekElevated
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.4%CVSS: 7.5Exploit: Elevated riskExposed services: Not assessed

A fix is available — apply it.

Netty's HTTP/3 codec (io.netty:netty-codec-http3) from 4.2.0.Final through 4.2.17.Final retains unbounded per-stream QPACK encoder state. QpackEncoder stores a queue and a dynamic-table index tracker for every encoded field section that references the QPACK dynamic table, keyed by the peer-controlled QUIC stream ID, and these entries are released only when the remote decoder sends a Section Acknowledgment or Stream Cancellation instruction — not when the HTTP/3 stream completes. There is no limit on the number of tracked streams, field sections, or retained bytes. A remote, unauthenticated HTTP/3 client can advertise a non-zero QPACK dynamic-table capacity, acknowledge the table insertion so the server reuses a dynamically indexed response header, and then omit all mandatory Section Acknowledgments while issuing sequential requests over a single QUIC connection, bypassing concurrent-stream limits and causing unbounded heap growth until the server exhausts memory (denial of service). Fixed in 4.2.18.Final.

CVSS v3
7.5
EG Score
7.5HIGHhigh confidence
EG Risk
65
EG Risk 65/100CISA 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
Severity75% × 45%
Exploitation40% × 40%
Automatability100% × 15%
CISA SSVC: Track at low or medium mission impact; Attend at high (mission-essential systems).
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
0.4%
EPSS %ILE
29th
KEV
Not listed

CISA SSVCTrack 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 public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (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 26, 2026

Last Modified

September 28, 2026

Advisory Details (2)

Auto-updated Sep 26, 2026
🔬 Proof of concept available. Patch available. Sources: github.
generic

Netty before 4.2.18.Final QpackEncoder Unbounded Memory Retention | Advisories | VulnCheck

https://www.vulncheck.com/advisories/netty-before-4.2.18-final-qpackencoder-unbounded-memory-retention
github Patch Available🟡 PoC Available

QpackEncoder retains unbounded per-stream dynamic-table trackers when a peer withholds Section Acknowledgments · Advisory · netty/netty · GitHub

https://github.com/netty/netty/security/advisories/GHSA-495p-pchh-r4mc

Vendor Advisories for CVE-2026-100660(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 32× in last 7d / 43× 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. 2026-10-05 00:53 UTCEG score recompute
  2. 2026-10-05 00:53 UTCGHSA enrichment
  3. 2026-10-04 23:21 UTCEPSS rescore
  4. 2026-10-04 13:14 UTCGHSA enrichment
  5. 2026-10-04 01:39 UTCEG score recompute
  6. 2026-10-04 01:38 UTCGHSA enrichment
  7. 2026-10-03 14:25 UTCEPSS rescore
  8. 2026-10-03 13:59 UTCGHSA enrichment
  9. 2026-10-03 02:22 UTCEG score recompute
  10. 2026-10-03 02:22 UTCGHSA enrichment
  11. 2026-10-02 14:43 UTCGHSA enrichment
  12. 2026-10-02 03:08 UTCEG score recompute
  13. 2026-10-02 03:08 UTCGHSA enrichment
  14. 2026-10-01 19:49 UTCEPSS rescore
  15. 2026-10-01 15:33 UTCGHSA enrichment
  16. 2026-10-01 03:52 UTCGHSA enrichment
  17. 2026-09-30 16:17 UTCEG score recompute
  18. 2026-09-30 16:17 UTCGHSA enrichment
  19. 2026-09-30 15:02 UTCEPSS rescore
  20. 2026-09-30 04:31 UTCGHSA enrichment
  21. 2026-09-29 16:52 UTCEG score recompute
  22. 2026-09-29 16:52 UTCGHSA enrichment
  23. 2026-09-29 15:20 UTCEPSS rescore
  24. 2026-09-29 05:17 UTCEG score recompute
  25. 2026-09-29 05:17 UTCGHSA enrichment
Show 18 more
  1. 2026-09-28 17:42 UTCEG score recompute
  2. 2026-09-28 17:42 UTCGHSA enrichment
  3. 2026-09-28 17:00 UTCEG score recompute
  4. 2026-09-28 17:00 UTCGHSA enrichment
  5. 2026-09-28 15:27 UTCEG score recompute
  6. 2026-09-28 15:27 UTCGHSA enrichment
  7. 2026-09-28 13:50 UTCEPSS rescore
  8. 2026-09-28 04:59 UTCGHSA enrichment
  9. 2026-09-27 17:24 UTCEG score recompute
  10. 2026-09-27 17:24 UTCGHSA enrichment
  11. 2026-09-27 16:36 UTCEG score recompute
  12. 2026-09-27 16:35 UTCGHSA enrichment
  13. 2026-09-27 13:44 UTCGHSA enrichment
  14. 2026-09-27 02:08 UTCEG score recompute
  15. 2026-09-27 02:08 UTCGHSA enrichment
  16. 2026-09-26 14:33 UTCEG score recompute
  17. 2026-09-26 13:37 UTCEG score recompute
  18. 2026-09-26 13:30 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-100660?
CVE-2026-100660 is a high vulnerability published on September 26, 2026. Netty's HTTP/3 codec (io.netty:netty-codec-http3) from 4.2.0.Final through 4.2.17.Final retains unbounded per-stream QPACK encoder state. QpackEncoder stores a queue and a dynamic-table index tracker for every encoded field section that references the QPACK dynamic table, keyed by the…
When was CVE-2026-100660 disclosed?
CVE-2026-100660 was first published on September 26, 2026, with the most recent update on September 28, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-100660 actively exploited?
CVE-2026-100660 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (29th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-100660?
CVE-2026-100660 has a CVSS base score of 7.5 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-100660?
A fix for CVE-2026-100660 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-100660 are linked in the Vendor Advisories panel on this page.

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