Issues

• text/html; example conflicts with RFC 9110

  whatwg/mimesniff#215 · Filter by author koal44 opened on Sep 18, 2026

• Is "the value of the last Content-Type header" correct?

  whatwg/mimesniff#214 · Filter by author domenic opened on Sep 7, 2026
  1

• Servo's implementation of Sniffing in a style context

  addition/proposalneeds teststopic: mime type sniffing
  whatwg/mimesniff#207 · Filter by author TimvdLippe opened on Jan 22, 2026
  2

• Are the abbreviations 0xTT and OxWS necessary?

  whatwg/mimesniff#206 · Filter by author evilpie opened on Jan 21, 2026
  2

• Some browsers don't sniff <!-- not followed by space or > as per standard

  compatinteropsecurity/privacy
  whatwg/mimesniff#205 · Filter by author valenting opened on Jan 21, 2026
  1

• Pattern for application/vnd.ms-fontobject prone to false-positives

  needs concrete proposalneeds teststopic: mime type sniffing
  whatwg/mimesniff#203 · Filter by author silverwind opened on Jan 14, 2026
  3

• Don't use "MIME"

  editorialneeds implementer interest
  whatwg/mimesniff#195 · Filter by author martinthomson opened on Dec 4, 2024
  1

• Algorithm for determining what is and is not a MIME type seems to be undefined.

  topic: mime type
  whatwg/mimesniff#194 · Filter by author MattMenke2 opened on Sep 10, 2024
  5

• Should Mac BinHex be sniffed?

  needs concrete proposalneeds implementer interesttopic: mime type sniffing
  whatwg/mimesniff#191 · Filter by author yuhong opened on Jun 25, 2024

• Web platform tests disagree on how to handle blob content-type validation

  needs tests
  whatwg/mimesniff#189 · Filter by author wisniewskit opened on Apr 26, 2024
  14

• Some context-specific sniffing algorithms don't check if supplied MIME type is undefined

  clarification
  whatwg/mimesniff#181 · Filter by author kemzeb opened on Nov 6, 2023
  2

• Various issues in the "Signature for mp3 without id3" algorithm

  clarificationtopic: mime type sniffing
  whatwg/mimesniff#168 · Filter by author simonwuelker opened on Apr 15, 2023
  1

• Confusing step in parse a vint

  whatwg/mimesniff#167 · Filter by author simonwuelker opened on Apr 15, 2023

• Navigating to a text/plain-labeled PNG file

  topic: mime type sniffing
  whatwg/mimesniff#157 · Filter by author annevk opened on Jan 17, 2022

• RFC 2046 does not define the term "internet media type"

  whatwg/mimesniff#155 · Filter by author GPHemsley opened on Sep 6, 2021
  2

• Browsers ignore tag-terminating byte when sniffing scriptable patterns

  topic: mime type sniffing
  whatwg/mimesniff#154 · Filter by author GPHemsley opened on Sep 4, 2021
  1

• Scope and structure of mimesniff

  meta
  whatwg/mimesniff#152 · Filter by author GPHemsley opened on Sep 3, 2021
  3

• Should isom brand be used to detect MP4?

  topic: mime type sniffing
  whatwg/mimesniff#149 · Filter by author evilpie opened on Aug 16, 2021
  1

• "parse a vint" algorithm does not align with "matches the signature for WebM" algorithm

  topic: mime type sniffing
  whatwg/mimesniff#146 · Filter by author Gallaecio opened on Jun 22, 2021
  1

• 7 - 7.1 incoherence

  clarification
  whatwg/mimesniff#145 · Filter by author Gallaecio opened on Jun 7, 2021

• Missing image codecs

  needs implementer interesttopic: mime type sniffing
  whatwg/mimesniff#143 · Filter by author jonsneyers opened on May 18, 2021
  29

• The "archive" MIME type definition excludes some "zip" MIME types.

  topic: mime type
  whatwg/mimesniff#140 · Filter by author nuno-andre opened on Apr 22, 2021
  2

• Supplied MIME type from file system is unclear

  whatwg/mimesniff#138 · Filter by author Jayman2000 opened on Feb 13, 2021
  1

• Step 5.2.8 in 7.3

  whatwg/mimesniff#127 · Filter by author asifmallik opened on Aug 23, 2020

• Issue with description of WebM sniffing

  whatwg/mimesniff#126 · Filter by author velezbeltran opened on Aug 21, 2020
  1