CVE-2026-58058: Nmap through 7.99 does not keep the IPv6 extension-header walk within the captured packet in ipv6_get_data_pri

Q: How do I fix CVE-2026-58058?

nmap: upgrade to newer than 7.99. Exact commands for each OS are on this page.

Q: Is CVE-2026-58058 being exploited?

CVE-2026-58058 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-58058 affect?

CVE-2026-58058 affects nmap. Severity is medium (CVSS 6.5). 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

Q: How urgent is CVE-2026-58058?

Priority 51/100. Public exploit reference; Remotely exploitable, no login, no user action

This week

MEDIUM 6.5REMOTEUPGRADE

CVE-2026-58058 is a medium-severity flaw (CVSS 6.5) affecting nmap. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.5% (top 27%)
CISA exploited list	No
Weakness	CWE-191
Published	2026-06-28
Last modified	2026-10-25

Publisher (CNA): VulnCheck · Vendor: nmap

Last updated 2026-10-25 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-06-28 02:16 UTCPublished CVE record published
2026-10-25 17:10 UTCUpdated Record last modified

nmap nmap UPGRADE

Affected: <= 7.99

Fixed in: newer than 7.99

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy nmap || rpm -q nmap || nmap --version

2. UPGRADE to newer than 7.99 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade nmap

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade nmap

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Exploit-DB: Nmap 7.99 - Extension Header Integer Underflow

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-58058?

nmap: upgrade to newer than 7.99. Exact commands for each OS are on this page.

Is CVE-2026-58058 being exploited?

CVE-2026-58058 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-58058 affect?

CVE-2026-58058 affects nmap. Severity is medium (CVSS 6.5). 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

How urgent is CVE-2026-58058?

Priority 51/100. Public exploit reference; Remotely exploitable, no login, no user action

References

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