Open-Source Security Intelligence

Know every vulnerability
before it knows you.

DevGuard continuously monitors your dependencies and alerts you when CVEs like this one affect your stack — with real-time threat intelligence built for developers.

Check if your repositories are affected!View on GitHub
Search

OSEC-2026-16

HighCVSS 8.7 / 10
Published Aug 20, 2026·Last modified Aug 22, 2026
Affected Components(1)
opamcohttp
< 6.3.0
Description

The issue is that the function normalizes the URI path before percent decoding it:

let resolve_local_file ~docroot ~uri =

  let path = Uri.(pct_decode (path (resolve "http" (of_string "/") uri))) in

  ...

Because %2f is decoded after Uri.resolve, encoded separators survive dot-segment normalization. For example, a request path like:

/static/..%2f..%2f..%2fetc/passwd

is normalized as a single encoded segment, then decoded into:

/static/../../../etc/passwd

afterwards.

Timeline

Risk Scores
Base Score
8.7

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability.

Threat Intelligence
6.6

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
N/A

Probability that this vulnerability will be exploited in the wild within the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

Browse More

High severity
Scan your project

Continuously monitor your dependencies and get alerted when vulnerabilities like this one affect your stack.

Checkout DevGuard