# CVE-2026-86287: Net::IP::LPM versions before 1.12 for Perl accept malformed prefix lengths

> Attackers can bypass IP allow-lists or deny-lists by providing malformed prefix lengths, causing the library to incorrectly accept or block all addresses.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 7 Sep 2026
- **Updated:** 8 Sep 2026
- **Also known as:** GHSA-456r-qjr2-xph9

## What is CVE-2026-86287?

CVE-2026-86287 is a high-severity vulnerability, published on 7 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Net::IP::LPM versions before 1.12 for Perl accept malformed prefix lengths.

Non-numeric and non-ASCII prefix lengths are accepted and treated as 0. Integers over 31 bits are silently truncated.  A single malformed mask will poison the lookup table.

The result is that the lookup will silently succeed for every address. An allow-list will allow every address, and a deny-list will block every address.

Weakness: CWE-1287 (Improper Validation of Specified Type of Input)

## Which versions are affected by CVE-2026-86287?


## How do I fix CVE-2026-86287?

No fix has been published for CVE-2026-86287 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-86287 being exploited?

There is no known exploitation of CVE-2026-86287 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-86287 and fix it if it is affected.

What it is: CVE-2026-86287 is a high-severity vulnerability, published on 7 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-86287 in the wild and no public exploit code.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-86287/ (Markdown: https://insights.sbomify.com/CVE-2026-86287/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-86287
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-86287
- OSV: https://osv.dev/vulnerability/CVE-2026-86287

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-86287/
Summaries are generated and may contain mistakes; the official description above is the record.