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.

CVSS v3.1 Score

6.5

MEDIUM

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

EPSS — Exploit Prediction

0.0028

Probability of exploitation

0.20%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-191 CWE-191

Affected Products

Vendor	Product	Versions
nmap	nmap	< 7.99

References

Advisories & Patches

https://github.com/nmap/nmap/commit/bb6754e76bb1686315008e1aa1c40202a513fb83 https://nmap.org/changelog.html https://www.vulncheck.com/advisories/nmap-integer-underflow-in-ipv6-extension-header-parsing

Other References

https://github.com/bikini/exploitarium/tree/main/nmap-ipv6-extlen-wrap-poc

Frequently Asked Questions

What is CVE-2026-58058? +

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. It has a CVSS v3.1 base score of 6.5 (MEDIUM).

How severe is CVE-2026-58058? +

CVE-2026-58058 has a CVSS v3.1 score of 6.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0028, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-58058? +

CVE-2026-58058 affects products from nmap, specifically: nmap. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-58058? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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