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.
CVE-2026-44373
MEDIUMNVD 5.35.3—Elevated
EchelonGraph scoreMEDIUM confidence
This medium-severity CVE scores 5.3 under NVD CVSS v3. EPSS exploit probability: 0.4%, top 69% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
Triggered by: NVD CVSS baseline
Sources: epss, nvd
5.3
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
- Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 5.3Exploit: NoneExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 5.3
- EG Score
- 5.3(medium)
- EPSS
- 31.3%
- KEV
- Not listed
Published
May 13, 2026
Last Modified
May 28, 2026
Advisory Details (5)
Auto-updated Jun 16, 2026Patch available. Sources: github_pr, github_release, github.
github Patch Available
Proxy scope bypass via percent-encoded path traversal in `routeRules` · Advisory · nitrojs/nitro · GitHub
https://github.com/nitrojs/nitro/security/advisories/GHSA-5w89-w975-hf9qgithub_release Patch Available
v3.0.260429-beta
Patch available: nitrojs/nitro v3.0.260429-beta
https://github.com/nitrojs/nitro/releases/tag/v3.0.260429-betagithub_release Patch Available
v2.13.4
Patch available: nitrojs/nitro v2.13.4
https://github.com/nitrojs/nitro/releases/tag/v2.13.4github_pr
fix(route-rules): reject out-of-scope requests
Fix merged in nitrojs/nitro PR #4223 on 2026-04-22 — awaiting tagged release
https://github.com/nitrojs/nitro/pull/4223github_pr Patch Available
fix(route-rules): reject out-of-scope requests
Patch available: nitrojs/nitro v2.13.4 (PR #4222 merged 2026-04-22)
https://github.com/nitrojs/nitro/pull/4222Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Frequently asked(5)
What is CVE-2026-44373?
CVE-2026-44373 is a medium vulnerability published on May 13, 2026. 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…
When was CVE-2026-44373 disclosed?
CVE-2026-44373 was first published in the National Vulnerability Database on May 13, 2026, with the most recent update on May 28, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-44373 actively exploited?
CVE-2026-44373 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 31.3% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-44373?
CVE-2026-44373 has a CVSS v3 base score of 5.3 (NVD).
How do I remediate CVE-2026-44373?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-44373, 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
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-44373
Is Your Infrastructure Affected by CVE-2026-44373?
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