osec-2026-16
Vulnerability from osv_ocaml
Published
2026-08-20 18:15
Modified
2026-08-20 18:15
Summary
Path traversal in Cohttp.Path.resolve_local_file
Details
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
- Aug 11th 2026: report to security@ocaml.org
- Aug 14th 2026: PR published on https://github.com/mirage/ocaml-cohttp/pull/1145
- Aug 20th 2026: fix released in v6.3.0 https://github.com/ocaml/opam-repository/pull/30528
Severity
7.5 (High)
{
"affected": [
{
"ecosystem_specific": {
"affected_bindings": [
"Cohttp.Path.resolve_local_file",
"Cohttp_async.Server.resolve_local_file",
"Cohttp_lwt_unix.Server.resolve_file",
"Cohttp_lwt.Make().resolve_local_file"
],
"opam_constraint": "cohttp {\u003c \"6.3.0\"}"
},
"package": {
"ecosystem": "opam",
"name": "cohttp",
"purl": "pkg:opam/cohttp"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "6.3.0"
}
],
"type": "ECOSYSTEM"
},
{
"events": [
{
"introduced": "0"
},
{
"fixed": "5f5a65ec3289c1cd8072bdf0ef22c181b4f11356"
}
],
"repo": "https://github.com/mirage/ocaml-cohttp.git",
"type": "GIT"
}
],
"versions": [
"0.9.1",
"0.9.2",
"0.9.3",
"0.9.4",
"0.9.5",
"0.9.6",
"0.9.7",
"0.9.8",
"0.9.9",
"0.9.10",
"0.9.11",
"0.9.12",
"0.9.13",
"0.9.14",
"0.9.15",
"0.9.16",
"0.10.0",
"0.10.1",
"0.11.0",
"0.11.1",
"0.11.2",
"0.12.0",
"0.13.0",
"0.14.0",
"0.15.0",
"0.15.1",
"0.15.2",
"0.16.0",
"0.16.1",
"0.17.0",
"0.17.1",
"0.17.2",
"0.18.0",
"0.18.1",
"0.18.2",
"0.18.3",
"0.19.0",
"0.19.1",
"0.19.2",
"0.19.3",
"0.20.0",
"0.20.1",
"0.20.2",
"0.21.0",
"0.21.1",
"0.22.0",
"0.99.0",
"1.0.0",
"1.0.2",
"1.1.0",
"1.1.1",
"1.2.0",
"2.0.0",
"2.1.2",
"2.1.3",
"2.2.0",
"2.3.0",
"2.4.0",
"2.5.0",
"2.5.1",
"2.5.2",
"2.5.2-1",
"2.5.3",
"2.5.4",
"2.5.5",
"2.5.6",
"2.5.7",
"2.5.8",
"3.0.0",
"4.0.0",
"4.1.1",
"4.1.2",
"5.0.0",
"5.1.0",
"5.2.0",
"5.3.0",
"5.3.1",
"6.0.0~alpha0",
"6.0.0~alpha1",
"6.0.0~alpha2",
"6.0.0~beta2",
"6.0.0",
"6.1.0",
"6.1.1",
"6.2.1",
"6.2.2"
]
}
],
"credits": [
{
"name": "Sapphire Livingstone",
"type": "REPORTER"
},
{
"name": "Sapphire Livingstone",
"type": "REMEDIATION_DEVELOPER"
},
{
"name": "Anil Madhavapeddy",
"type": "REMEDIATION_DEVELOPER"
},
{
"name": "Anil Madhavapeddy",
"type": "REMEDIATION_REVIEWER"
},
{
"name": "Michael Dales",
"type": "REMEDIATION_REVIEWER"
},
{
"name": "Edwin Torok",
"type": "REMEDIATION_REVIEWER"
},
{
"name": "Patrick Ferris",
"type": "REMEDIATION_REVIEWER"
},
{
"name": "Hannes Mehnert",
"type": "COORDINATOR"
}
],
"database_specific": {
"cwe": [
"CWE-22"
],
"human_link": "https://github.com/ocaml/security-advisories/tree/main/advisories/2026/OSEC-2026-16.md",
"osv": "https://github.com/ocaml/security-advisories/tree/generated-osv/2026/OSEC-2026-16.json"
},
"details": "The issue is that the function normalizes the URI path before percent\ndecoding it:\n\n```OCaml\nlet resolve_local_file ~docroot ~uri =\n\n let path = Uri.(pct_decode (path (resolve \"http\" (of_string \"/\") uri))) in\n\n ...\n```\n\nBecause `%2f` is decoded after Uri.resolve, encoded separators survive\ndot-segment normalization. For example, a request path like:\n\n```\n/static/..%2f..%2f..%2fetc/passwd\n```\n\nis normalized as a single encoded segment, then decoded into:\n\n```\n/static/../../../etc/passwd\n```\n\nafterwards.\n\n## Timeline\n\n- Aug 11th 2026: report to security@ocaml.org\n- Aug 14th 2026: PR published on \u003chttps://github.com/mirage/ocaml-cohttp/pull/1145\u003e\n- Aug 20th 2026: fix released in v6.3.0 \u003chttps://github.com/ocaml/opam-repository/pull/30528\u003e",
"id": "OSEC-2026-16",
"modified": "2026-08-20T18:15:00Z",
"published": "2026-08-20T18:15:00Z",
"references": [],
"schema_version": "1.7.4",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
],
"summary": "Path traversal in Cohttp.Path.resolve_local_file"
}
Loading…
Loading…
Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Loading…
The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Loading…
Loading…