# CVE-2026-49942: Net::CIDR::Set versions through 0.20 for Perl did not validate network masks

> Attackers can bypass network restrictions by using Unicode digits or leading zeros in CIDR masks, allowing access to larger networks than intended.

- **Severity:** High 7.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 4 Jun 2026
- **Updated:** 4 Jun 2026
- **Also known as:** DEBIAN-CVE-2026-49942, GHSA-fff7-gx98-vr3g, UBUNTU-CVE-2026-49942

## What is CVE-2026-49942?

CVE-2026-49942 is a high-severity vulnerability in RRWO Net::CIDR::Set, published on 4 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Net::CIDR::Set versions through 0.20 for Perl did not validate network masks.

The mask portion of a network mask could contain Unicode digits such as the Arabic-Indic One (U+0661), or non-digits, which were ignored.   This could allow network masks to accept larger networks.

Leading zeros were also accepted, but treated as decimal instead of octal.  This could lead to confusion about what networks are acceptable.

Weakness: CWE-1289 (Improper Validation of Unsafe Equivalence in Input)

## Which versions are affected by CVE-2026-49942?

It affects 1 product.


Products: Rrwo Net\.

## How do I fix CVE-2026-49942?

Upgrade to a fixed version.

## Is CVE-2026-49942 being exploited?

There is no known exploitation of CVE-2026-49942 in the wild and no public exploit code.

## Other vulnerabilities in RRWO Net::CIDR::Set

- [CVE-2026-49941](https://insights.sbomify.com/CVE-2026-49941/): Net::CIDR::Set versions through 0.20 for Perl did not validate IP addresses (high 7.5)
- [CVE-2026-49940](https://insights.sbomify.com/CVE-2026-49940/): Net::CIDR::Set versions through 0.20 for Perl accept non-ASCII IP addresses and netmasks (medium 6.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-49942 and fix it if it is affected.

What it is: CVE-2026-49942 is a high-severity vulnerability in RRWO Net::CIDR::Set, published on 4 Jun 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-2026-49942 in the wild and no public exploit code.

Affected product: RRWO Net::CIDR::Set. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-49942/ (Markdown: https://insights.sbomify.com/CVE-2026-49942/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-49942
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-49942
- OSV: https://osv.dev/vulnerability/CVE-2026-49942

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-49942/
Summaries are generated and may contain mistakes; the official description above is the record.