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.

Routine

CVSS

6.5

Moderate

Exploitation

None reported

No vendor assessment

CISA KEV

Not listed

Not in the Known Exploited Vulnerabilities catalog

EPSS

0.0145

73rd percentile

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

Product	Fixed in	Fix	Released
Linux
nmap · Debian 14	7.99+dfsg-2	DEBIAN-CVE-2026-58058	Jul 22, 2026
nmap · Fedora 43	4:7.92-8.fc43	FEDORA-2026-602D919DBC	Jul 1, 2026
nmap · sles 15.7	7.92-150600.9.3.1	SUSE-SU-2026:3340-1	Jul 28, 2026
nmap · sles 16.0	7.92-160000.3.1	SUSE-SU-2026:22814-1	Jul 15, 2026
nmap-debuginfo · Fedora 43	4:7.92-8.fc43	FEDORA-2026-602D919DBC	Jul 1, 2026
nmap-debugsource · Fedora 43	4:7.92-8.fc43	FEDORA-2026-602D919DBC	Jul 1, 2026
nmap-ncat · Fedora 43	4:7.92-8.fc43	FEDORA-2026-602D919DBC	Jul 1, 2026
nmap-ncat-debuginfo · Fedora 43	4:7.92-8.fc43	FEDORA-2026-602D919DBC	Jul 1, 2026

Details

Published
June 28, 2026
Weakness
Integer Underflow (Wrap or Wraparound)
Vendor advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-58058

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