CVE-2026-86251
High · CVSS 8.2Published 2026-09-06
CVSS
8.2
High
EPSS
—
exploit probability
Active Exploit
No
not yet listed
What is CVE-2026-86251?
h3 versions before 1.15.9 contain a path traversal vulnerability in the serveStatic utility. A double-decoding flaw allows a request path containing double-encoded dot sequences (e.g. %252e%252e) to be decoded to %2e%2e, which survives resolveDotSegments() because that function only checks for literal '.' characters. When the resulting asset ID is resolved by URL-based backends (CDN, S3, object storage), %2e%2e is interpreted as '..' per RFC 3986, enabling path traversal to read arbitrary files from the backend.
CVSS Score Explained
CVSS 8.2 is High severity. Exploitation is likely straightforward and the impact is significant — data loss, privilege escalation, or remote code execution are common outcomes. Patch as soon as possible.
EPSS Exploitation Probability
No EPSS score yet — model needs more data on this CVE.
References & Patches
- ›https://github.com/h3js/h3/security/advisories/GHSA-72gr-qfp7-vwhw
- ›https://www.vulncheck.com/advisories/h3-before-1.15.9-path-traversal-via-double-decoding
Track vulnerabilities for your stack
Tell us what tech you run — Node.js, Python, Java, nginx, whatever — and get a weekly email when new CVEs affect it.
Recent CVEs
- CVE-2026-76160Rejected reason: This CVE ID has been rejected or withdrawn by its CVE Numbering Authority.—
- CVE-2026-76161Rejected reason: This CVE ID has been rejected or withdrawn by its CVE Numbering Authority.—
- CVE-2026-86150A security vulnerability has been detected in Tenda CP3 27.5.57.101. Impacted is an unknown function of the file custom-x/softap/hostapd. Such manipulation of the argument wpa_passphrase leads to hard-coded credentials. The attack can be launched remotely. The exploit has been disclosed publicly and may be used.2.0
- CVE-2026-86148A security flaw has been discovered in Tenda CP3 27.5.57.101. This vulnerability affects the function SystemAsh of the file Apis/system.c of the component Kylin. The manipulation of the argument AlarmVoiceURL results in os command injection. It is possible to launch the attack remotely.9.4
- CVE-2026-86149A weakness has been identified in Tenda CP3 27.5.57.101. This issue affects some unknown processing of the file Net/NetCheckPing.cpp. This manipulation of the argument interface_name/host causes os command injection. The attack can be initiated remotely.9.4
- CVE-2026-67277RouterOS accepts a "related" btest connection before the corresponding primary session has completed authentication. An unauthenticated client can use this state to start an IPv4 UDP test. With "random-data=false", the sender transmits an uninitialized tail from a kernel packet buffer. A separate unchecked, inverted packet-size interval causes unsigned integer underflow, anomalously large fragmented output, and can restart the RouterOS kernel.
This issue was fixed in versions: 6.49.21 (Long-term), 7.23.4 (Long-term) and 7.24.2 (Stable)8.8