diff --git a/advisories/github-reviewed/2025/06/GHSA-gmhf-gg8w-jw42/GHSA-gmhf-gg8w-jw42.json b/advisories/github-reviewed/2025/06/GHSA-gmhf-gg8w-jw42/GHSA-gmhf-gg8w-jw42.json
new file mode 100644
index 00000000000..c2d87704e08
--- /dev/null
+++ b/advisories/github-reviewed/2025/06/GHSA-gmhf-gg8w-jw42/GHSA-gmhf-gg8w-jw42.json
@@ -0,0 +1,65 @@
+{
+  "schema_version": "1.4.0",
+  "id": "GHSA-gmhf-gg8w-jw42",
+  "modified": "2025-06-05T00:37:19Z",
+  "published": "2025-06-05T00:37:19Z",
+  "aliases": [
+    "CVE-2025-48995"
+  ],
+  "summary": "SignXML's signature verification with HMAC is vulnerable to a timing attack",
+  "details": "When verifying signatures with X509 certificate validation turned off and HMAC shared secret set (`signxml.XMLVerifier.verify(require_x509=False, hmac_key=...`), prior versions of SignXML are vulnerable to a potential timing attack. The verifier may leak information about the correct HMAC when comparing it with the user supplied hash, allowing users to reconstruct the correct HMAC for any data.",
+  "severity": [
+    {
+      "type": "CVSS_V4",
+      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N"
+    }
+  ],
+  "affected": [
+    {
+      "package": {
+        "ecosystem": "PyPI",
+        "name": "signxml"
+      },
+      "ranges": [
+        {
+          "type": "ECOSYSTEM",
+          "events": [
+            {
+              "introduced": "0"
+            },
+            {
+              "fixed": "4.0.4"
+            }
+          ]
+        }
+      ]
+    }
+  ],
+  "references": [
+    {
+      "type": "WEB",
+      "url": "https://github.com/XML-Security/signxml/security/advisories/GHSA-gmhf-gg8w-jw42"
+    },
+    {
+      "type": "ADVISORY",
+      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-48995"
+    },
+    {
+      "type": "WEB",
+      "url": "https://github.com/XML-Security/signxml/commit/1b501faaacf34cf978a52dbc6915ec11e27611cd"
+    },
+    {
+      "type": "PACKAGE",
+      "url": "https://github.com/XML-Security/signxml"
+    }
+  ],
+  "database_specific": {
+    "cwe_ids": [
+      "CWE-208"
+    ],
+    "severity": "MODERATE",
+    "github_reviewed": true,
+    "github_reviewed_at": "2025-06-05T00:37:19Z",
+    "nvd_published_at": "2025-06-02T17:15:41Z"
+  }
+}
\ No newline at end of file