Vulnerability report

Active exploitation observed Confirmed confidence Not in CISA KEV

CVE-2026-44373

nitro Proxy scope bypass Path Traversal

Nitrojs / nitro · affected before 3.0.260429-beta

Watch CVE-2026-44373 Browse KEV feed
Severity
CVSS 5.3 · Medium
Confidence
Confirmed
Exploit status
Observed in sensors
EPSS
0.6%
First observed
05 Oct 2026
Last observed
22 Oct 2026

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2026-44373 is an unauthenticated vulnerability affecting Nitrojs nitro, nitropack. Nitro is a next generation server toolkit. Prior to 3.0.260429-beta, an attacker could bypass a proxy route rule by sending...

Is it exploited?

Yes. Previdian sensors observed exploitation attempts with confirmed confidence.

Who is affected?

Nitrojs / nitro affected before 3.0.260429-beta.

What should we do?

Patch immediately, validate internet-facing exposure, and monitor for matching requests.

Overview

Nitro is a next generation server toolkit

Nitro is a next generation server toolkit. Prior to 3.0.260429-beta, an attacker could bypass a proxy route rule by sending percent-encoded path traversal (..%2f) in the URL, causing Nitro to forward a request that the upstream resolved outside the configured scope.

This vulnerability is fixed in 3.0.260429-beta.

nitrojs Affected
nitro
Before 3.0.260429-beta
nitrojs Affected
nitropack
Before 2.13.4
Published
13 May 2026
Exploited Since
05 Oct 2026
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
None

Tags

edge

CVE References

Exploitation evidence

Why Previdian marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

Previdian

Recorded 21 Oct 2026

Previdian independently recorded this as exploited after first seeing it in honeypot sensors.

Active exploitation observed

Previdian sensor

First observed 05 Oct 2026

Previdian first observed exploitation attempts targeting this vulnerability in our honeypot sensors.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

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Source Added
Previdian Sensors First 2026-10-21 13:34 UTC

Operational indicators for this CVE are listed under Detection.

Sensor telemetry

First-party evidence of exploitation activity

Previdian sensors recorded exploitation attempts targeting this vulnerability. The cards and chart show volume, unique attackers, and daily activity.

830

Attempts observed

263

Unique attacker IPs

10

Attacker countries

AT · BE · BR · CA · DE · JP · NL · SG · TW · US

21

Sensors observed

CVE-2026-44373 exploitation attempts over the last 19 days

Daily events observed by Previdian sensors

Updated 22 Oct 2026

0
10
8
0
72
23
24
51
27
33
42
33
51
147
72
40
70
112
15
4 Oct 8 Oct 12 Oct 16 Oct 22 Oct

First observed 05 Oct 2026 · Last observed 22 Oct 2026

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Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
User-Agents
Callback hosts
3
39
0

Request targets and User-Agents available in Pro. Callback host details available in Enterprise.

Scanner coverage

No scanner integrations recorded yet.

Virtual patch status

Previdian virtual patch guidance is available for this CVE.

AWS WAF Cloudflare ModSecurity

Attacker IP Indicators

Attacker IP indicators observed · available in Pro and Enterprise.

Sensor-derived attacker IP indicators are available to Pro and Enterprise accounts under Detection and through the Pro API.

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Virtual Patch Detail

Compensating WAF rules for this CVE.

Available

Enterprise feature. Virtual patch rule content and deployable vendor exports (ModSecurity, Cloudflare, AWS WAF) are available to Previdian Enterprise users.

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Risk and context

Severity, weaknesses, and research context

CVSS v3.1

5.3 Medium

Potential damage if exploited. Separate from whether attackers are using it.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

EPSS

0.6%

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

Weaknesses

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') CWE-22

Timeline

From disclosure to observed exploitation

  1. 14:18 UTC

    Virtual patch available

    Compensating WAF rule available to block exploitation

  2. 01:02 UTC

    Indicators of compromise added (263)

    Indicators of compromise recorded

  3. 01:02 UTC

    Observed by Previdian sensors

    Evidence-backed exploitation signal

  4. 20:26 UTC

    CVE published

    Vulnerability disclosed publicly

  5. 20:15 UTC

    CVE ID reserved

    Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2026-44373

Sample API response 
{
  "cve_id": "CVE-2026-44373",
  "confidence": "Confirmed",
  "cvss_score": 5.3,
  "cvss_estimated": false,
  "epss_score": 0.00574,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": true
  },
  "sensor_telemetry": { "attempts": 830, "sensors": 21 }
}