Critical Vulnerability Information Security Advisory Advisory ID: Mozilla Foundation Security Advisory 2025-62 Product: Thunderbird Fixed Version: Thunderbird 128.13 Release Date: July 26, 2025 Impact Level: High Vulnerability Details 1. CVE-2025-8027: JavaScript Engine Writes Only Partial Return Value to Stack - Reporter: Nan Wang - Impact: High - Description: On certain platforms, writes only a partial return value space to the stack, which may lead to crashes or similar issues when browsing emails. 2. CVE-2025-8028: Large Branch Table May Cause Truncated Instructions - Reporter: Gary Kwong - Impact: High - Description: In m64-WASM, branch table instructions with a large number of entries may cause label jumps far away from the instruction address, resulting in truncated and incorrect instruction computation. 3. CVE-2025-8029: JavaScript URLs Executed on Object and Embed Tags - Reporter: Williambrook - Impact: Moderate - Description: Thunderbird executes javascript:URLs on object and embed tags. 4. CVE-2025-8030: Potential User-Assisted Code Execution in "Copy as cURL" Command - Reporter: Aminah Basheer M K - Impact: Moderate - Description: Unsafe escaping in the "Copy as cURL" feature may be exploited to trigger unintended code execution by users. 5. CVE-2025-8031: URL Username and Password Not Properly Stripped in CSP Reports - Reporter: Tom Schuster - Impact: Moderate - Description: Username and password portions in URLs are not correctly stripped from CSP reports, potentially leading to leakage of HTTP basic authentication credentials. 6. CVE-2025-8032: XSLT Documents Can Bypass CSP - Reporter: Joe Turner - Impact: Moderate - Description: XSLT document loading does not properly propagate the source document, allowing it to bypass its Content Security Policy (CSP). 7. CVE-2025-8033: Incorrect JavaScript Generator State Machine - Reporter: Shahar Fazin - Impact: Low - Description: The JavaScript engine does not correctly handle closed generators and may resume them, leading to null pointer dereference. 8. CVE-2025-8034: Memory Safety Vulnerabilities in Firefox ESR 115.26, Firefox ESR 128.13, Thunderbird ESR 128.13, Firefox ESR 140.1, Thunderbird ESR 140.1, Firefox 141, and Thunderbird 141 - Reporter: The Mozilla Fuzzing Team - Impact: High - Description: Memory safety vulnerabilities exist, showing evidence of memory corruption. We assume some of these may be exploitable to run arbitrary code. 9. CVE-2025-8035: Memory Safety Vulnerabilities in Firefox ESR 128.13, Thunderbird ESR 128.13, Firefox ESR 140.1, Thunderbird ESR 140.1, Firefox 141, and Thunderbird 141 - Reporter: The Mozilla Fuzzing Team - Impact: High - Description: Memory safety vulnerabilities exist, showing evidence of memory corruption. We assume some of these may be exploitable to run arbitrary code.