CVE-2026-62143 Server-Side Request Forgery protection bypass in misp-modules html_to_markdown via IPv4-mapped IPv6 addresses
An authenticated attacker can bypass SSRF protections in MISP modules using IPv4-mapped IPv6 addresses to access internal services and metadata.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-62143?
CVE-2026-62143 is a high-severity server-side request forgery vulnerability in misp-modules, published on 13 Jul 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
A Server-Side Request Forgery (SSRF) protection bypass existed in the html_to_markdown expansion module of misp-modules.
The module attempts to prevent requests to loopback, private, link-local, and other restricted IP address ranges. However, IP addresses were compared against the blocked ranges without first normalising IPv4-mapped IPv6 addresses.
An authenticated attacker able to invoke the module could supply an IPv4-mapped IPv6 address, such as:
http://[::ffff:127.0.0.1]/ http://[::ffff:169.254.169.254]/
Alternatively, the attacker could use a hostname that resolves to an IPv4-mapped IPv6 address. These addresses were treated as IPv6 addresses and therefore did not match the corresponding blocked IPv4 ranges.
Successful exploitation could cause the misp-modules server to connect to services available through its loopback interface, internal network, or link-local network. This could expose internal web services, administrative interfaces, or cloud instance metadata, with retrieved content potentially returned to the attacker as converted Markdown.
The vulnerability has been addressed by normalising IPv4-mapped IPv6 addresses to their underlying IPv4 representation before applying the blocked-range checks. URLs without a valid hostname are now also rejected.
Weakness: CWE-918
Which versions are affected by CVE-2026-62143?
How do I fix CVE-2026-62143?
No fix has been published for CVE-2026-62143 yet. Limit exposure of the affected software until one is available.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-62143 being exploited?
There is no known exploitation of CVE-2026-62143 in the wild and no public exploit code.
Sources
Also known as GHSA-xv9c-v5pw-jxvf.