{"id":"CVE-2026-112991","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-112991","generatedAt":"2026-10-28T02:58:19.232Z","title":"The html_to_markdown expansion module in MISP Modules contains a server-side request forgery (SSRF) vulnerability in its is_safe_url() URL validation function.","description":"The html_to_markdown expansion module in MISP Modules contains a server-side request forgery (SSRF) vulnerability in its is_safe_url() URL validation function. The BLOCKED_RANGES list used to reject unsafe destination addresses was incomplete, omitting several critical IP address ranges. Specifically, the following ranges were not blocked: 0.0.0.0/8 (unspecified, which routes to loopback on Linux), 100.64.0.0/10 (carrier-grade NAT per RFC 6598), ::/128 (IPv6 unspecified), fc00::/7 (IPv6 Unique Local Addresses), and fe80::/10 (IPv6 link-local). The existing list only covered IPv4 loopback (127.0.0.0/8), RFC 1918 private ranges, IPv4 link-local (169.254.0.0/16), and IPv6 loopback (::1/128).\n\nAn authenticated user with the ability to create or modify MISP attributes that trigger the html_to_markdown expansion module could supply URLs pointing to these unblocked internal address ranges. Because the module fetches the URL server-side to convert HTML content to Markdown, the request is made from the MISP server's network context. This allows an attacker to probe and read responses from internal services, carrier-grade NAT infrastructure, or link-local endpoints that would otherwise be unreachable from external networks. IPv4-mapped IPv6 forms (e.g., [::ffff:0.0.0.0]) also bypassed the existing checks.\n\nThe security impact is primarily confidentiality: an attacker can read data served by internal services reachable from the MISP server. The MISP instance itself is not compromised, but it is abused as a proxy to access otherwise restricted network resources.","published":"2026-10-19T23:17:36.000Z","lastModified":"2026-10-20T20:17:17.000Z","status":"Deferred","sourceIdentifier":"5a6e4751-2f3f-4070-9419-94fb35b644e8","cvss":{"version":"4.0","score":6.3,"severity":"MEDIUM","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:N/SC:H/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M"},"cwe":["CWE-20","CWE-918"],"affected":[],"epss":{"score":0.00324,"percentile":0.25201,"date":"2026-10-26","history":[{"date":"2026-10-20","score":0.00312,"percentile":0.22725}]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"low","text":"Lower severity and a low EPSS score (0.32%). Track it; it rarely justifies an emergency change on its own."},"changes":[{"kind":"new","label":"New CVE","at":"2026-10-19T23:17:36.000Z","detail":{"score":"6.3","severity":"MEDIUM","publishedAt":"2026-10-19T23:17:36.350Z"},"summary":"New CVE, medium severity (CVSS 6.3)."}],"references":[{"url":"https://github.com/misp/misp-modules/commit/98a1c2c2f297665dd8d4609e9cd644007a57516b","source":"5a6e4751-2f3f-4070-9419-94fb35b644e8"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-112991","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}