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ETK-2026-2549Zero's internal tracking ID, independent of the CVE number.

ETK-2026-2549Zero's internal tracking ID, independent of the CVE number.

validatedZero produced an exploit or a check.

GHSA-w2jw-cxmw-937m ↗

check availableZero validated a working check for it.not proven exploitableZero has a detection check, but hasn't produced a full working exploit yet.
awaiting cvepublic pocExploit code has been published by someone. Source signals can also carry a PoC (Proof of Concept).kevAttacks confirmed in the real world.
other:h2o commits up to dde5b5e
fixed in commits a336d0d and above
ETK-2026-2549Zero's internal tracking ID, independent of the CVE number., no cve assigned
cvss7.5cna vendorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
−6h37mTTV
19mAI analysisAnalysis: how long the AI spent reversing this signal.
Check if you are vulnerable
timeline
0 = cve.org, not yet published
trigger signal −38h13mcheck available−6h37magent stopped
−36h
−24h
−12h
0

description

H2O is affected by a use-after-free in HTTP/3 connection timer management when request streaming is enabled. A remote peer can trigger connection handling that may crash a worker while streams remain active.

mitigation

Upgrade h2o to commits a336d0d and above or later.

fixed in commits a336d0d and above

check
available
exploit
no
automationDeterministic: a check that runs on its own, the same request on every target. Contextual: an agentic technique that needs to be applied per target, for bugs that depend on contextual flows.
deterministic
auth requiredWhether an attacker needs an account first, based on the CVSS vector's Privileges Required.
no
EPSSEstimate of the chance this CVE is exploited in the next 30 days. Refreshed daily.
–
agent run time
19m
cve.org record, t = 0The moment cve.org publishes the CVE in full.
not published yet
Δ to public pocExploit code has been published by someone. Source signals can also carry a PoC (Proof of Concept).
–
Δ to kevAttacks confirmed in the real world.
–

outcome

Check only, differential: the check fires on the vulnerable build and is silent on the patched one.

source signals

Public signals that triggered or updated the pipeline. These are inputs for the deltas above.

  1. 2026-10-23 09:04Z

this entry in the feed

GET /api/v1/feed/ETK-2026-2549

{
  "etk_id": "ETK-2026-2549",
  "cve_id": null,
  "display_id": "ETK-2026-2549",
  "ghsa_id": "GHSA-w2jw-cxmw-937m",
  "euvd_id": null,
  "status": "published",
  "anchor_state": "awaiting_cve",
  "title": "Use-after-free in H2O HTTP/3 timer handling",
  "summary": "H2O is affected by a use-after-free in HTTP/3 connection timer management when request streaming is enabled. A remote peer can trigger connection handling that may crash a worker while streams remain active.",
  "mitigation": "Upgrade h2o to commits a336d0d and above or later.",
  "vendor": "other",
  "product": "other:h2o",
  "affected": [
    {
      "affected_notes": [
        "commits up to dde5b5e"
      ],
      "affected_ranges": [],
      "ecosystem": "other",
      "fixed_versions": [
        "commits a336d0d and above"
      ],
      "package_name": "h2o",
      "purl": null
    }
  ],
  "cwes": null,
  "cvss_score": 7.5,
  "cvss_src": "cna_vendor",
  "cvss_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
  "epss_score": null,
  "epss_percentile": null,
  "epss_asof": null,
  "automation": "deterministic",
  "check": true,
  "check_confidence_basis": "differential",
  "exploit": false,
  "pipeline_minutes": 18.79285623333333,
  "t0_at": null,
  "signals": {
    "check": {
      "at": "2026-10-24T16:41:37.919839+00:00",
      "days": -0.2753695415509259,
      "is_lower_bound": true,
      "measured_at": "2026-10-24T23:18:10.034086+00:00",
      "url": null
    },
    "trigger_signal": {
      "at": "2026-10-23T09:04:53+00:00",
      "days": -1.592556113761574,
      "is_lower_bound": true,
      "measured_at": "2026-10-24T23:18:10.034086+00:00",
      "url": "https://github.com/h2o/h2o/security/advisories/GHSA-w2jw-cxmw-937m"
    }
  }
}

published 2026-10-24 16:22Z
last change 2026-10-24 23:06Z

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