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Out-of-bounds ReadWeakness · CWE-125

CVE-2026-56015

CRITICAL · 9.1 CVSS v3.1 Published 2026-07-03
Patch available
A vendor patch is available. No clean upgrade release — apply the published patch.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click Patch available 7 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Net::IP::LPM versions through 1.10 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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Net::IP::LPM Perl module versions 1.10 and earlier lack validation of prefix length in the add() function. When a prefix length exceeding the address width (32 for IPv4, 128 for IPv6) is provided, addPrefixToTrie() reads past the end of the packed address buffer by up to 32 bytes. This heap out-of-bounds read is detectable by memory sanitizers but not exposed through the module's public API.

MitigationAdd input validation in add() to reject prefix lengths exceeding 32 for IPv4 or 128 for IPv6 addresses before passing to addPrefixToTrie(). Alternatively, upgrade to a patched version once available.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check installed Net::IP::LPM version
    Run 'perl -MNet::IP::LPM -e "print $Net::IP::LPM::VERSION"' or locate the module file (typically in site/lib/Net/IP/LPM.pm) and read the $VERSION variable
    Affected if Version is 1.10 or earlier (the vulnerable version range)
  2. Confirm the add() function lacks prefix length validation
    Examine the Net::IP::LPM source code, specifically the add() subroutine, for any validation that rejects prefix lengths greater than 32 for IPv4 or 128 for IPv6 before calling addPrefixToTrie()
    Affected if No such validation exists in the add() function, allowing oversized prefix lengths to reach addPrefixToTrie()
  3. Detect heap out-of-bounds read via memory sanitizer
    Run Perl code that exercises add() with an oversized prefix length (e.g., 33+ for IPv4 or 129+ for IPv6) under a memory sanitizer-enabled build of the module (ASan or MSan)
    Affected if The sanitizer reports a heap out-of-bounds read of up to 32 bytes beyond the packed address buffer

A user is affected if they have Net::IP::LPM version 1.10 or earlier and can observe the out-of-bounds read through memory sanitizers, since the vulnerability is not exposed through the module's public API without such instrumentation.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Patch available Apply the vendor patch
Vendor patch security.metacpan.org →
Interim mitigation

Add input validation in add() to reject prefix lengths exceeding 32 for IPv4 or 128 for IPv6 addresses before passing to addPrefixToTrie(). Alternatively, upgrade to a patched version once available.

Recommended fix High confidence
  1. Download the vendor patch from https://security.metacpan.org/patches/N/Net-IP-LPM/1.10/CVE-2026-56015-r2.patch
  2. Review the patch to understand the fix (validation of prefix length against address width)
  3. Apply the patch to the Net-IP-LPM-1.10 source code using 'patch -p1 < CVE-2026-56015-r2.patch'
  4. Reinstall the patched module using 'perl Makefile.PL && make && make test && make install'
  5. Verify the module loads correctly and test that prefix lengths >32 (IPv4) or >128 (IPv6) are now rejected

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,390
Get the patch applied

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,224.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-56015 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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