From 7019936c75f50a8d87400fa0d1315a8250503b4c Mon Sep 17 00:00:00 2001
From: Jan Friedrich <43271715+FreeAndNil@users.noreply.github.com>
Date: Fri, 10 Apr 2026 21:35:03 +0200
Subject: [PATCH] Improve GHSA-4f7c-pmjv-c25w

---
 .../GHSA-4f7c-pmjv-c25w.json                  | 34 ++++++++++++++++---
 1 file changed, 30 insertions(+), 4 deletions(-)

diff --git a/advisories/unreviewed/2026/04/GHSA-4f7c-pmjv-c25w/GHSA-4f7c-pmjv-c25w.json b/advisories/unreviewed/2026/04/GHSA-4f7c-pmjv-c25w/GHSA-4f7c-pmjv-c25w.json
index 52bd95619e9d0..16e7bdb98299f 100644
--- a/advisories/unreviewed/2026/04/GHSA-4f7c-pmjv-c25w/GHSA-4f7c-pmjv-c25w.json
+++ b/advisories/unreviewed/2026/04/GHSA-4f7c-pmjv-c25w/GHSA-4f7c-pmjv-c25w.json
@@ -1,19 +1,40 @@
 {
   "schema_version": "1.4.0",
   "id": "GHSA-4f7c-pmjv-c25w",
-  "modified": "2026-04-10T18:31:18Z",
+  "modified": "2026-04-10T18:31:27Z",
   "published": "2026-04-10T18:31:18Z",
   "aliases": [
     "CVE-2026-40021"
   ],
+  "summary": "Apache Log4net: Silent log event loss in XmlLayout and XmlLayoutSchemaLog4J due to unescaped XML 1.0 forbidden characters",
   "details": "Apache Log4net's  XmlLayout https://logging.apache.org/log4net/manual/configuration/layouts.html#layout-list  and  XmlLayoutSchemaLog4J https://logging.apache.org/log4net/manual/configuration/layouts.html#layout-list , in versions before 3.3.0, fail to sanitize characters forbidden by the  XML 1.0 specification https://www.w3.org/TR/xml/#charsets  in MDC property keys and values, as well as the identity field that may carry attacker-influenced data. This causes an exception during serialization and the silent loss of the affected log event.\n\nAn attacker who can influence any of these fields can exploit this to suppress individual log records, impairing audit trails and detection of malicious activity.\n\nUsers are advised to upgrade to Apache Log4net 3.3.0, which fixes this issue.",
   "severity": [
     {
       "type": "CVSS_V4",
-      "score": "CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/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"
+      "score": "CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N"
+    }
+  ],
+  "affected": [
+    {
+      "package": {
+        "ecosystem": "NuGet",
+        "name": "log4net"
+      },
+      "ranges": [
+        {
+          "type": "ECOSYSTEM",
+          "events": [
+            {
+              "introduced": "0"
+            },
+            {
+              "fixed": "3.3.0"
+            }
+          ]
+        }
+      ]
     }
   ],
-  "affected": [],
   "references": [
     {
       "type": "ADVISORY",
@@ -23,6 +44,10 @@
       "type": "WEB",
       "url": "https://github.com/apache/logging-log4net/pull/280"
     },
+    {
+      "type": "PACKAGE",
+      "url": "https://github.com/apache/logging-log4net"
+    },
     {
       "type": "WEB",
       "url": "https://lists.apache.org/thread/q8otftjswhk69n3kxslqg7cobr0x4st7"
@@ -46,7 +71,8 @@
   ],
   "database_specific": {
     "cwe_ids": [
-      "CWE-116"
+      "CWE-116",
+      "CWE-235"
     ],
     "severity": "MODERATE",
     "github_reviewed": false,