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Fencer Vulns
medium 6.5

CVE-2026-58058 json

Nmap - Integer Underflow in IPv6 Extension Header Parsing

published 2026-06-28 4 mo ago modified 2026-10-25 14 d ago also EUVD-2026-39978

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.5%
EPSS 1.5% chance of exploitation in 30 days, percentile 73%
public exploits
1
Exploit-DB

Summary

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.

Patch / fix

  • nmap Debian 14 7.99+dfsg-2

debian advisories DEBIAN-CVE-2026-58058

  • nmap SLE Module for Package Hub 15 SP7, SLE Module for Basesystem 15 SP7 7.92-150600.9.3.1
  • nmap SLES 16.0, Linux Micro Extras 6.2, SLES for SAP applications 16.0 7.92-160000.3.1
  • nmap SLES LTSS Extended Security 12 SP5 6.46-3.9.1

suse advisories SUSE-SU-2026:3340-1SUSE-SU-2026:3333-1SUSE-SU-2026:22739-1SUSE-SU-2026:22814-1

  • nmap Azure Linux 3.0 7.95-4

azure linux advisories AZL-91391

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-58058 updated cvss 6.5

nmap: Nmap: Denial of Service via crafted IPv6 response

  • Red Hat Enterprise Linux 6 nmap, nmap-frontend Red Hat Enterprise Linux 7 nmap, nmap-ncat, nmap-frontend Red Hat Enterprise Linux 8 nmap, nmap-ncat Red Hat Enterprise Linux 9 nmap, nmap-ncat Red Hat Enterprise Linux 10 nmap Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-8, openshift/ose-rhel-coreos-9
    +1 more products
    Red Hat OpenShift Container Platform 5 openshift/ose-rhel-coreos-9
    affected: workaround, no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Timeline

  1. Published
  2. First public exploit (EDB-52647)

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
4 mo ago

Exploit prediction

1.45% chance of exploitation in the next 30 days, higher than 73% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • EDB-52647 Nmap 7.99 - Extension Header Integer Underflow dos, 2026-08-17
  • github.com https://github.com/bikini/exploitarium/tree/main/nmap-ipv6-extlen-wrap-poc referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
CNA 4.0 6.9 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N
CNA 4.0 6.9 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected products

  • Nmap Nmap

Classification

Weakness
  • CWE-191 Integer Underflow (Wrap or Wraparound)

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.