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path: root/src/html/template/state_string.go
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2026-03-05html/template: properly escape URLs in meta content attributesRoland Shoemaker
The meta tag can include a content attribute that contains URLs, which we currently don't escape if they are inserted via a template action. This can plausibly lead to XSS vulnerabilities if untrusted data is inserted there, the http-equiv attribute is set to "refresh", and the content attribute contains an action like `url={{.}}`. Track whether we are inside of a meta element, if we are inside of a content attribute, _and_ if the content attribute contains "url=". If all of those are true, then we will apply the same URL escaping that we use elsewhere. Also add a new GODEBUG, htmlmetacontenturlescape, to allow disabling this escaping for cases where this behavior is considered safe. The behavior can be disabled by setting htmlmetacontenturlescape=0. Fixes CVE-2026-27142 Fixes #77954 Change-Id: I9bbca263be9894688e6ef1e9a8f8d2f4304f5873 Reviewed-on: https://go-internal-review.googlesource.com/c/go/+/3360 Reviewed-by: Neal Patel <nealpatel@google.com> Reviewed-by: Nicholas Husin <husin@google.com> Reviewed-on: https://go-review.googlesource.com/c/go/+/752181 Reviewed-by: Dmitri Shuralyov <dmitshur@google.com> LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
2023-10-02html/template: support parsing complex JS template literalsRoland Shoemaker
This change undoes the restrictions added in CL 482079, which added a blanket ban on using actions within JS template literal strings, and adds logic to support actions while properly applies contextual escaping based on the correct context within the literal. Since template literals can contain both normal strings, and nested JS contexts, logic is required to properly track those context switches during parsing. ErrJsTmplLit is deprecated, and the GODEBUG flag jstmpllitinterp no longer does anything. Fixes #61619 Change-Id: I0338cc6f663723267b8f7aaacc55aa28f60906f2 Reviewed-on: https://go-review.googlesource.com/c/go/+/507995 LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Auto-Submit: Roland Shoemaker <roland@golang.org> Reviewed-by: Damien Neil <dneil@google.com>
2023-09-06html/template: support HTML-like comments in script contextsRoland Shoemaker
Per Appendix B.1.1 of the ECMAScript specification, support HTML-like comments in script contexts. Also per section 12.5, support hashbang comments. This brings our parsing in-line with how browsers treat these comment types. Thanks to Takeshi Kaneko (GMO Cybersecurity by Ierae, Inc.) for reporting this issue. Fixes #62196 Fixes CVE-2023-39318 Change-Id: Id512702c5de3ae46cf648e268cb10e1eb392a181 Reviewed-on: https://team-review.git.corp.google.com/c/golang/go-private/+/1976593 Run-TryBot: Roland Shoemaker <bracewell@google.com> Reviewed-by: Tatiana Bradley <tatianabradley@google.com> Reviewed-by: Damien Neil <dneil@google.com> Reviewed-by: Dmitri Shuralyov <dmitshur@google.com> Reviewed-on: https://go-review.googlesource.com/c/go/+/526156 LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Roland Shoemaker <roland@golang.org> Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
2023-04-04html/template: disallow actions in JS template literalsRoland Shoemaker
ECMAScript 6 introduced template literals[0][1] which are delimited with backticks. These need to be escaped in a similar fashion to the delimiters for other string literals. Additionally template literals can contain special syntax for string interpolation. There is no clear way to allow safe insertion of actions within JS template literals, as handling (JS) string interpolation inside of these literals is rather complex. As such we've chosen to simply disallow template actions within these template literals. A new error code is added for this parsing failure case, errJsTmplLit, but it is unexported as it is not backwards compatible with other minor release versions to introduce an API change in a minor release. We will export this code in the next major release. The previous behavior (with the cavet that backticks are now escaped properly) can be re-enabled with GODEBUG=jstmpllitinterp=1. This change subsumes CL471455. Thanks to Sohom Datta, Manipal Institute of Technology, for reporting this issue. Fixes CVE-2023-24538 Fixes #59234 [0] https://tc39.es/ecma262/multipage/ecmascript-language-expressions.html#sec-template-literals [1] https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Template_literals Reviewed-on: https://team-review.git.corp.google.com/c/golang/go-private/+/1802457 Reviewed-by: Damien Neil <dneil@google.com> Run-TryBot: Damien Neil <dneil@google.com> Reviewed-by: Julie Qiu <julieqiu@google.com> Reviewed-by: Roland Shoemaker <bracewell@google.com> Change-Id: Ia221fefdb273bd0f066dffc2abcf2a616801d2f2 Reviewed-on: https://go-review.googlesource.com/c/go/+/482079 TryBot-Bypass: Michael Knyszek <mknyszek@google.com> Run-TryBot: Michael Knyszek <mknyszek@google.com> Reviewed-by: Matthew Dempsky <mdempsky@google.com> Auto-Submit: Michael Knyszek <mknyszek@google.com>
2018-02-20html/template: make more use of stringerDaniel Martí
The code was maintaining manual versions of it in multiple places - replace all of them. Change-Id: I04c3063877b05ba914de9f5dddb33ffe09f308fe Reviewed-on: https://go-review.googlesource.com/95356 Run-TryBot: Daniel Martí <mvdan@mvdan.cc> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>