Vulnerability · Published Jun 28, 2026 · Assigned by VulnCheck
CVE-2026-58058Nmap - Integer Underflow in IPv6 Extension Header Parsing
Medium 6.5
In plain English
A medium-severity security flaw in Nmap from Nmap. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 1.5% (higher than 74% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | nmap | no fix listed | DEBIAN-CVE-2026-58058 |
| Debian:13 | nmap | no fix listed | DEBIAN-CVE-2026-58058 |
| Debian:14 | nmap | 7.99+dfsg-2 | DEBIAN-CVE-2026-58058 |
| Ubuntu:22.04:LTS | nmap | no fix listed | UBUNTU-CVE-2026-58058 |
| Ubuntu:24.04:LTS | nmap | no fix listed | UBUNTU-CVE-2026-58058 |
| Ubuntu:25.10 | nmap | no fix listed | UBUNTU-CVE-2026-58058 |
| Ubuntu:26.04:LTS | nmap | no fix listed | UBUNTU-CVE-2026-58058 |
| Ubuntu:26.10 | nmap | no fix listed | UBUNTU-CVE-2026-58058 |
Affected products (as reported)
Weakness: CWE-191 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
References
- Proof of Concept exploit, third-party-advisory
- Fix commit (dev tree) patch
- Nmap Change Log release-notes
- VulnCheck Advisory: Nmap - Integer Underflow in IPv6 Extension Header Parsing third-party-advisory