# CVE-2026-58058: Nmap - Integer Underflow in IPv6 Extension Header Parsing

CVE-2026-58058 is fixed in 5 products on 1 platform, first by FEDORA-2026-602D919DBC, released July 1, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-58058
- Priority: Routine
- CVSS: 6.5 (Moderate)
- EPSS: 0.0145
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jun 28, 2026
- Weakness: Integer Underflow (Wrap or Wraparound)
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-58058

## Description

Nmap through 7.99 does not keep the IPv6 extension-header walk within the captured packet in ipv6_get_data_primitive (libnetutil/netutil.cc), so the pointer advances past the buffer and the remaining-length computation underflows to a large value. A scanned target or on-path attacker returning a crafted IPv6 response with a truncated extension header can trigger out-of-bounds reads and a crash during raw IPv6 scans.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | nmap Debian 14 | 7.99+dfsg-2 | [DEBIAN-CVE-2026-58058](https://patchblox.com/security/data/fix/linux/debian-cve-2026-58058.md) | Jul 22, 2026 |
| Linux | nmap Fedora 43 | 4:7.92-8.fc43 | [FEDORA-2026-602D919DBC](https://patchblox.com/security/data/fix/linux/fedora-2026-602d919dbc.md) | Jul 1, 2026 |
| Linux | nmap sles 15.7 | 7.92-150600.9.3.1 | [SUSE-SU-2026:3340-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-3340-1.md) | Jul 28, 2026 |
| Linux | nmap sles 16.0 | 7.92-160000.3.1 | [SUSE-SU-2026:22814-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22814-1.md) | Jul 15, 2026 |
| Linux | nmap-debuginfo Fedora 43 | 4:7.92-8.fc43 | [FEDORA-2026-602D919DBC](https://patchblox.com/security/data/fix/linux/fedora-2026-602d919dbc.md) | Jul 1, 2026 |
| Linux | nmap-debugsource Fedora 43 | 4:7.92-8.fc43 | [FEDORA-2026-602D919DBC](https://patchblox.com/security/data/fix/linux/fedora-2026-602d919dbc.md) | Jul 1, 2026 |
| Linux | nmap-ncat Fedora 43 | 4:7.92-8.fc43 | [FEDORA-2026-602D919DBC](https://patchblox.com/security/data/fix/linux/fedora-2026-602d919dbc.md) | Jul 1, 2026 |
| Linux | nmap-ncat-debuginfo Fedora 43 | 4:7.92-8.fc43 | [FEDORA-2026-602D919DBC](https://patchblox.com/security/data/fix/linux/fedora-2026-602d919dbc.md) | Jul 1, 2026 |

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Data as of 2026-11-09T01:18:40Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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