CVE-2021-29946

Ports that were written as an integer overflow above the bounds of a 16-bit integer could have bypassed port blocking restrictions when used in the Alt-Svc header. This vulnerability affects Firefox ESR < 78.10, Thunderbird < 78.10, and Firefox < 88.

• CWE-190

• https://bugzilla.mozilla.org/show_bug.cgi?id=1698503Permissions Required, Vendor Advisory
• https://www.mozilla.org/security/advisories/mfsa2021-14/Release Notes, Vendor Advisory
• https://www.mozilla.org/security/advisories/mfsa2021-15/Release Notes, Vendor Advisory
• https://www.mozilla.org/security/advisories/mfsa2021-16/Release Notes, Vendor Advisory
• https://bugzilla.mozilla.org/show_bug.cgi?id=1698503Permissions Required, Vendor Advisory
• https://www.mozilla.org/security/advisories/mfsa2021-14/Release Notes, Vendor Advisory
• https://www.mozilla.org/security/advisories/mfsa2021-15/Release Notes, Vendor Advisory
• https://www.mozilla.org/security/advisories/mfsa2021-16/Release Notes, Vendor Advisory

Published

Jun 24, 2021

Last Modified

Jun 17, 2026

Status

Modified

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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• CVE-2021-29940An issue was discovered in the through crate through 2021-02…9.8
• CVE-2021-29941An issue was discovered in the reorder crate through 2021-02…7.3
• CVE-2021-29942An issue was discovered in the reorder crate through 2021-02…7.3
• CVE-2021-29943When using ConfigurableInternodeAuthHadoopPlugin for authent…9.1
• CVE-2021-29944Lack of escaping allowed HTML injection when a webpage was v…6.1
• CVE-2021-29945The WebAssembly JIT could miscalculate the size of a return …6.5
• CVE-2021-29947Mozilla developers and community members reported memory saf…8.8
• CVE-2021-29948Signatures are written to disk before and read during verifi…2.5
• CVE-2021-29949When loading the shared library that provides the OTR protoc…7.8
• CVE-2021-29950Thunderbird unprotects a secret OpenPGP key prior to using i…7.5
• CVE-2021-29951The Mozilla Maintenance Service granted SERVICE_START access…6.5
• CVE-2021-29952When Web Render components were destructed, a race condition…7.5