Quick answer
Direct answer
Risk scores
| CVSS metric | What it means |
|---|---|
| Attack vector (AV:L) | Local access needed |
| Attack complexity (AC:L) | Low complexity |
| Privileges required (PR:N) | No privileges required |
| User interaction (UI:N) | No user interaction |
| Scope (S:U) | Scope unchanged |
| Confidentiality (C:L) | Low confidentiality impact |
| Integrity (I:H) | High integrity impact |
| Availability (A:L) | Low availability impact |
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:L
About Ocaml Opam
CVE-2026-41082 affects Ocaml Opam, a product from Ocaml. Before acting, confirm where Ocaml Opam runs in your estate, who owns it and whether it is reachable from the internet, because exposure decides real risk more than the score alone.
What the flaw is
In plain terms: In OCaml opam before 2.5.1, a .install field containing a destination filepath can use ../ to reach a parent directory.
The weakness class is Path Traversal. An attacker can reach files outside the intended folder by tampering with a file path.
Based on its CVSS vector, the flaw needs local or adjacent access, needs no login, and needs no user interaction. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.
Affected versions and timeline
| Field | Detail |
|---|---|
| Product | Ocaml Opam |
| Affected versions | Opam before 2.5.1; Debian Linux 11.0; Enterprise Linux 10.0 |
| Published | Apr 16, 2026 |
| Last modified | Jul 15, 2026 |
| Added to CISA KEV | Not listed |
| Assigning CNA | cve@mitre.org |
How to detect it
- Inventory every instance of Ocaml Opam and record the running version against the affected range above.
- Check external attack surface scans for internet facing instances of the component.
- Review logs on affected systems for unusual requests, errors or new processes around the vulnerable function.
- Confirm with an authenticated vulnerability scan once your scanner has a check for this CVE.
How to fix it
- Apply the fixed version of Ocaml Opam named in the vendor advisory.
- If patching must wait, restrict network access to the affected service and put it behind authentication or a web application firewall rule.
- Rescan after the change to prove the exposure is gone, then close the ticket.
CTEM action plan
| CTEM stage | What to do for this CVE |
|---|---|
| Scope | Add every business service that depends on Ocaml Opam to the current CTEM cycle. |
| Discover | Find all instances, including shadow and cloud deployments, and record versions and exposure. |
| Prioritize | Rank using EPSS and CVSS together with asset exposure and business impact. |
| Validate | Confirm the flaw is reachable and exploitable in your environment and that compensating controls work. |
| Mobilize | Assign the fix to the asset owner with a due date matched to the priority, then verify closure. |
CWE References
Technical References
Frequently asked questions
Related CVEs
In OCaml before 4.14.3 and 5.x before 5.4.1, a buffer over-read in Marshal deserialization (runtime/intern.c) enables remote code execution through a multi-phase attack chain. The vulnerability stems from missing bounds validation in the readblock() function, which performs unbounded memcpy() operations using attacker-controlled lengths from crafted Marshal data.
Exim before 4.99.5 allows directory traversal to access files outside of the spool area, and consequently gain privileges, because arguments related to queue-name are mishandled.
Joplin is an open source note-taking and to-do application that organises notes and lists into notebooks. Versions prior to 3.5.7 contain a path traversal vulnerability in the importer which allows overwriting arbitrary files on disk. The OneNote converter does not sanitize the names of embedded files before writing them to disk. As a result, it's possible for an attacker to create a malicious .one file that includes file names containing ../../, that are then interpreted as part of the target path when extracting attachments from the .one file. This issue has been patched in version 3.5.7.
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