{"id":74623,"date":"2025-09-13T04:59:51","date_gmt":"2025-09-13T04:59:51","guid":{"rendered":""},"modified":"2025-11-01T16:17:09","modified_gmt":"2025-11-01T22:17:09","slug":"cve-2025-36855-buffer-over-read-vulnerability-in-diasymreader-dll-affecting-eol-asp-net-versions","status":"publish","type":"post","link":"https:\/\/www.ameeba.com\/blog\/cve-2025-36855-buffer-over-read-vulnerability-in-diasymreader-dll-affecting-eol-asp-net-versions\/","title":{"rendered":"<strong>CVE-2025-36855: Buffer Over-read Vulnerability in DiaSymReader.dll affecting EOL ASP.NET versions<\/strong>"},"content":{"rendered":"<p><strong>Overview<\/strong><\/p>\n<p>The cybersecurity world has recently seen the surfacing of a critical vulnerability, CVE-2025-36855, that resides in DiaSymReader.dll. It primarily affects End Of Life (EOL) ASP.NET versions, causing a significant risk to <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-25180-underprivileged-software-manipulates-gpu-system-calls-for-unauthorized-access\/\"  data-wpil-monitor-id=\"88758\">systems running these software<\/a> components. This vulnerability is of particular concern due to its potential for system compromise or data leakage, making it a <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-54887-significant-security-vulnerability-in-jwe-ruby-encryption-implementation\/\"  data-wpil-monitor-id=\"82674\">significant threat to data security<\/a> and integrity.<\/p>\n<p><strong>Vulnerability Summary<\/strong><\/p>\n<p>CVE ID: CVE-2025-36855<br \/>\nSeverity: High (CVSS score: 8.8)<br \/>\nAttack Vector: Local<br \/>\nPrivileges Required: Low<br \/>\nUser Interaction: None<br \/>\nImpact: <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-22404-potential-system-compromise-due-to-use-after-free-vulnerability\/\"  data-wpil-monitor-id=\"85640\">System compromise<\/a> or data leakage<\/p>\n<p><strong>Affected Products<\/strong><\/p><div id=\"ameeb-3522576700\" class=\"ameeb-content-2 ameeb-entity-placement\"><div style=\"border-left: 4px solid #555; padding-left: 20px; margin: 48px 0; font-family: Roboto, sans-serif; color: #ffffff; line-height: 1.6; max-width: 700px;\">\r\n  <h2 style=\"margin-top: 0; font-size: 20px; font-weight: 600; display: flex; align-items: center;\">\r\n    <a href=\"https:\/\/www.ameeba.com\/chat\" style=\"display: inline-flex; align-items: center; margin-right: 8px;\">\r\n      <img decoding=\"async\" src=\"https:\/\/www.ameeba.com\/blog\/wp-content\/uploads\/2025\/10\/Best-App-icon-Ameeba.png\" alt=\"Ameeba Chat Icon\" style=\"width: 40px; height: 40px;\" \/>\r\n    <\/a>\r\n    A new way to communicate\r\n  <\/h2>\r\n\r\n  <p style=\"margin-bottom: 12px;\">\r\n    Ameeba Chat is built on encrypted identity, not personal profiles.\r\n  <\/p>\r\n\r\n  <p style=\"margin-bottom: 16px;\">\r\n    Message, call, share files, and coordinate with identities kept separate.\r\n  <\/p>\r\n\r\n  <ul style=\"list-style: none; padding-left: 0; margin-bottom: 20px;\">\r\n    <li>\u2022 Encrypted identity<\/li>\r\n    <li>\u2022 Ameeba Chat authenticates access<\/li>\r\n    <li>\u2022 Aliases and categories<\/li>\r\n    <li>\u2022 End-to-end encrypted chat, calls, and files<\/li>\r\n    <li>\u2022 Secure notes for sensitive information<\/li>\r\n  <\/ul>\r\n\r\n  <p style=\"font-style: italic; font-weight: 600; margin-bottom: 24px;\">\r\n    Private communication, rethought.\r\n  <\/p>\r\n\r\n  <div style=\"display: flex; flex-wrap: wrap; gap: 12px;\">\r\n    <a href=\"https:\/\/www.ameeba.com\/chat\/download\" style=\"background-color: #ffffff; color: #000000; padding: 10px 20px; text-decoration: none; border-radius: 6px; font-weight: 500;\">Download Ameeba Chat<\/a>\r\n    <a href=\"https:\/\/www.ameeba.com\/chat\" style=\"border: 1px solid #ffffff; color: #ffffff; padding: 10px 20px; text-decoration: none; border-radius: 6px; font-weight: 500;\">Learn More<\/a>\r\n  <\/div>\r\n<\/div>\r\n<\/div>\n<p>Product | Affected Versions<\/p>\n<p>ASP.NET | 6.0.0 <= 6.0.36\nASP.NET | 8.0.0 <= 8.0.11\nASP.NET | <= 9.0.0\n\n<strong>How the Exploit Works<\/strong><\/p>\n<p>This <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-54910-exploiting-heap-based-buffer-overflow-in-microsoft-office\/\"  data-wpil-monitor-id=\"89535\">exploit takes advantage of a buffer<\/a> over-read in DiaSymReader.dll. A <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-45968-insecure-direct-object-reference-vulnerability-in-system-pdv-v1-0\/\"  data-wpil-monitor-id=\"83006\">buffer<\/a> over-read occurs when the system reads from a buffer using access mechanisms such as indexes or pointers that reference memory locations after the buffer. In this case, an attacker can manipulate these mechanisms to read sensitive information from other memory locations, <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2022-45134-critical-vulnerability-in-mahara-leading-to-potential-system-compromise\/\"  data-wpil-monitor-id=\"82913\">potentially leading to system<\/a> compromise or data leakage.<\/p>\n<p><strong>Conceptual Example Code<\/strong><\/p>\n<p>A conceptual example of this <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-53104-command-injection-vulnerability-in-gluestack-ui-s-github-actions-workflow\/\"  data-wpil-monitor-id=\"92097\">vulnerability in action<\/a> might look something like this:<\/p><div id=\"ameeb-803634570\" class=\"ameeb-content ameeb-entity-placement\"><div class=\"poptin-embedded\" data-id=\"f6b387694f681\"><\/div>\r\n\r\n\r\n\r\n\r\n\r\n<\/div>\n<pre><code class=\"\" data-line=\"\">BufferedStream bs = new BufferedStream(new MemoryStream());\nbyte[] buffer = new byte[10];\nbs.Read(buffer, 11, 2); \/\/ Over-read<\/code><\/pre>\n<p>In this example, the attacker is forcing the <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-9253-stack-based-buffer-overflow-on-linksys-wi-fi-range-extenders-leading-to-potential-system-compromise\/\"  data-wpil-monitor-id=\"84207\">system to read beyond the length of the buffer<\/a>, which can result in unexpected behavior or data leakage.<\/p>\n<p><strong>Impact Summary<\/strong><\/p>\n<p>The successful exploitation of this <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-24775-high-severity-unrestricted-file-upload-vulnerability-in-made-i-t-forms\/\"  data-wpil-monitor-id=\"83067\">vulnerability can lead to severe<\/a> consequences, including the compromise of the entire system or the leakage of sensitive data. Given the high severity score of 8.8, it is crucial to address this issue urgently.<\/p>\n<p><strong>Mitigation Guidance<\/strong><\/p>\n<p>As a mitigation strategy, it is recommended to apply the vendor patch. However, if this is not feasible due to the EOL status of the affected software, using a Web Application Firewall (WAF) or Intrusion Detection System (IDS) can provide temporary mitigation. Furthermore, any self-contained applications targeting the <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-30403-heap-buffer-overflow-vulnerability-in-mvfst-impacts-quic-sessions\/\"  data-wpil-monitor-id=\"82343\">impacted versions are also vulnerable<\/a> and must be recompiled and redeployed.<br \/>\nPlease note that this CVE affects only End Of Life (EOL) software components. The vendor, Microsoft, has indicated there will be no future updates nor support provided upon inquiry. This underscores the importance of keeping software components updated and migrating from EOL versions as soon as <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-54742-data-deserialization-vulnerability-in-wpevently-leading-to-possible-system-compromise\/\"  data-wpil-monitor-id=\"86420\">possible to maintain a secure and robust system<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Overview The cybersecurity world has recently seen the surfacing of a critical vulnerability, CVE-2025-36855, that resides in DiaSymReader.dll. It primarily affects End Of Life (EOL) ASP.NET versions, causing a significant risk to systems running these software components. This vulnerability is of particular concern due to its potential for system compromise or data leakage, making it [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"om_disable_all_campaigns":false,"footnotes":""},"categories":[1],"tags":[],"vendor":[],"product":[],"attack_vector":[],"asset_type":[],"severity":[],"exploit_status":[],"class_list":["post-74623","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/posts\/74623","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/comments?post=74623"}],"version-history":[{"count":11,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/posts\/74623\/revisions"}],"predecessor-version":[{"id":85305,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/posts\/74623\/revisions\/85305"}],"wp:attachment":[{"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/media?parent=74623"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/categories?post=74623"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/tags?post=74623"},{"taxonomy":"vendor","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/vendor?post=74623"},{"taxonomy":"product","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/product?post=74623"},{"taxonomy":"attack_vector","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/attack_vector?post=74623"},{"taxonomy":"asset_type","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/asset_type?post=74623"},{"taxonomy":"severity","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/severity?post=74623"},{"taxonomy":"exploit_status","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/exploit_status?post=74623"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}