CVE-2026-19773

CRITICALPre-NVD 9.89.8—
EchelonGraph scoreHIGH confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-09-15. a secondary CVSS source baseline 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this week
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 9.8Exploit: None knownExposed: 0

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

libwebsockets HTTP/2 HPACK Path Header Parsing Out-Of-Bounds Write Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of libwebsockets. Authentication is not required to exploit this vulnerability.

The specific flaw exists within the parsing of HTTP/2 HPACK path header. The issue results from the lack of proper validation of user-supplied data, which can result in a write past the end of an allocated buffer. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-31036.

CVSS v3
9.8
EG Score
9.8(high)
EG Risk
59(Track)
EG Risk 59/100SSVC: Track

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%
Exploitation1% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
49%
KEV
Not listed

Published

September 15, 2026

Last Modified

September 18, 2026

Advisory Details (2)

Auto-updated Sep 18, 2026
Upstream fix merged — awaiting tagged release. Sources: github_commit.
generic

ZDI-26-590 - TrendAI™ Zero Day Initiative™ (ZDI)

https://www.zerodayinitiative.com/advisories/ZDI-26-590/
github_commit

commit 824151862f37 (warmcat/libwebsockets)

Fix landed in warmcat/libwebsockets commit 824151862f37 — awaiting tagged release

https://github.com/warmcat/libwebsockets/commit/824151862f37bc72f46d9a3e01d5b9408d313a0b

Vendor Advisories for CVE-2026-19773(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 / 75× 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. 2026-09-25 12:16 UTCGHSA enrichment
  2. 2026-09-25 08:10 UTCGHSA enrichment
  3. 2026-09-25 04:05 UTCGHSA enrichment
  4. 2026-09-25 00:00 UTCGHSA enrichment
  5. 2026-09-24 19:53 UTCGHSA enrichment
  6. 2026-09-24 15:47 UTCEG score recompute
  7. 2026-09-24 15:47 UTCGHSA enrichment
  8. 2026-09-24 11:42 UTCGHSA enrichment
  9. 2026-09-24 07:36 UTCGHSA enrichment
  10. 2026-09-24 03:31 UTCGHSA enrichment
  11. 2026-09-23 23:26 UTCGHSA enrichment
  12. 2026-09-23 19:20 UTCGHSA enrichment
  13. 2026-09-23 14:18 UTCEG score recompute
  14. 2026-09-23 14:18 UTCGHSA enrichment
  15. 2026-09-23 10:12 UTCGHSA enrichment
  16. 2026-09-23 06:07 UTCGHSA enrichment
  17. 2026-09-23 02:01 UTCGHSA enrichment
  18. 2026-09-22 21:55 UTCGHSA enrichment
  19. 2026-09-22 17:49 UTCEG score recompute
  20. 2026-09-22 17:49 UTCGHSA enrichment
  21. 2026-09-22 13:42 UTCGHSA enrichment
  22. 2026-09-22 09:37 UTCGHSA enrichment
  23. 2026-09-22 05:30 UTCGHSA enrichment
  24. 2026-09-22 01:24 UTCGHSA enrichment
  25. 2026-09-21 21:19 UTCEG score recompute
Show 50 more
  1. 2026-09-21 21:19 UTCGHSA enrichment
  2. 2026-09-21 17:13 UTCGHSA enrichment
  3. 2026-09-21 13:07 UTCGHSA enrichment
  4. 2026-09-21 09:01 UTCGHSA enrichment
  5. 2026-09-21 04:55 UTCGHSA enrichment
  6. 2026-09-21 00:34 UTCGHSA enrichment
  7. 2026-09-20 20:28 UTCEG score recompute
  8. 2026-09-20 20:28 UTCGHSA enrichment
  9. 2026-09-20 16:22 UTCGHSA enrichment
  10. 2026-09-20 12:16 UTCGHSA enrichment
  11. 2026-09-20 08:10 UTCGHSA enrichment
  12. 2026-09-20 04:04 UTCGHSA enrichment
  13. 2026-09-19 23:59 UTCGHSA enrichment
  14. 2026-09-19 19:53 UTCGHSA enrichment
  15. 2026-09-19 15:48 UTCEG score recompute
  16. 2026-09-19 15:47 UTCGHSA enrichment
  17. 2026-09-19 11:38 UTCGHSA enrichment
  18. 2026-09-19 07:31 UTCGHSA enrichment
  19. 2026-09-19 03:25 UTCGHSA enrichment
  20. 2026-09-18 23:19 UTCEG score recompute
  21. 2026-09-18 23:19 UTCGHSA enrichment
  22. 2026-09-18 19:27 UTCEPSS rescore
  23. 2026-09-18 19:14 UTCGHSA enrichment
  24. 2026-09-18 16:12 UTCGHSA enrichment
  25. 2026-09-18 12:06 UTCGHSA enrichment
  26. 2026-09-18 08:00 UTCGHSA enrichment
  27. 2026-09-18 03:54 UTCGHSA enrichment
  28. 2026-09-17 23:49 UTCEG score recompute
  29. 2026-09-17 23:49 UTCGHSA enrichment
  30. 2026-09-17 19:19 UTCGHSA enrichment
  31. 2026-09-17 14:52 UTCGHSA enrichment
  32. 2026-09-17 10:46 UTCGHSA enrichment
  33. 2026-09-17 06:37 UTCGHSA enrichment
  34. 2026-09-17 02:29 UTCGHSA enrichment
  35. 2026-09-16 22:20 UTCGHSA enrichment
  36. 2026-09-16 17:55 UTCEG score recompute
  37. 2026-09-16 17:55 UTCGHSA enrichment
  38. 2026-09-16 14:07 UTCEPSS rescore
  39. 2026-09-16 12:52 UTCGHSA enrichment
  40. 2026-09-16 08:47 UTCGHSA enrichment
  41. 2026-09-16 04:27 UTCEG score recompute
  42. 2026-09-16 04:27 UTCGHSA enrichment
  43. 2026-09-16 04:17 UTCEG score recompute
  44. 2026-09-16 04:17 UTCGHSA enrichment
  45. 2026-09-16 00:48 UTCEG score recompute
  46. 2026-09-16 00:48 UTCGHSA enrichment
  47. 2026-09-15 20:42 UTCEG score recompute
  48. 2026-09-15 19:23 UTCEG score recompute
  49. 2026-09-15 18:24 UTCEG score recompute
  50. 2026-09-15 18:22 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-19773?
CVE-2026-19773 is a critical vulnerability published on September 15, 2026. libwebsockets HTTP/2 HPACK Path Header Parsing Out-Of-Bounds Write Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of libwebsockets. Authentication is not required to exploit this vulnerability. The specific flaw…
When was CVE-2026-19773 disclosed?
CVE-2026-19773 was first published in the National Vulnerability Database on September 15, 2026, with the most recent update on September 18, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-19773 actively exploited?
CVE-2026-19773 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 51.3% of all scored CVEs.
What is the CVSS score of CVE-2026-19773?
CVE-2026-19773 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-19773?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-19773, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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