From 994692847a2cd3efd319f0cb61a07c0012c8a4ff Mon Sep 17 00:00:00 2001 From: Roland Shoemaker Date: Fri, 9 Jan 2026 11:12:01 -0800 Subject: [release-branch.go1.26] html/template: properly escape URLs in meta content attributes 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. Updates #77954 Fixes #77972 Fixes CVE-2026-27142 Change-Id: I9bbca263be9894688e6ef1e9a8f8d2f4304f5873 Reviewed-on: https://go-internal-review.googlesource.com/c/go/+/3360 Reviewed-by: Neal Patel Reviewed-by: Nicholas Husin Reviewed-on: https://go-internal-review.googlesource.com/c/go/+/3643 Reviewed-by: Damien Neil Reviewed-on: https://go-review.googlesource.com/c/go/+/752081 Auto-Submit: Gopher Robot Reviewed-by: Cherry Mui TryBot-Bypass: Gopher Robot Reviewed-by: Dmitri Shuralyov --- src/html/template/state_string.go | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) (limited to 'src/html/template/state_string.go') diff --git a/src/html/template/state_string.go b/src/html/template/state_string.go index eed1e8bcc0..f5a70b2231 100644 --- a/src/html/template/state_string.go +++ b/src/html/template/state_string.go @@ -36,12 +36,14 @@ func _() { _ = x[stateCSSBlockCmt-25] _ = x[stateCSSLineCmt-26] _ = x[stateError-27] - _ = x[stateDead-28] + _ = x[stateMetaContent-28] + _ = x[stateMetaContentURL-29] + _ = x[stateDead-30] } -const _state_name = "stateTextstateTagstateAttrNamestateAfterNamestateBeforeValuestateHTMLCmtstateRCDATAstateAttrstateURLstateSrcsetstateJSstateJSDqStrstateJSSqStrstateJSTmplLitstateJSRegexpstateJSBlockCmtstateJSLineCmtstateJSHTMLOpenCmtstateJSHTMLCloseCmtstateCSSstateCSSDqStrstateCSSSqStrstateCSSDqURLstateCSSSqURLstateCSSURLstateCSSBlockCmtstateCSSLineCmtstateErrorstateDead" +const _state_name = "stateTextstateTagstateAttrNamestateAfterNamestateBeforeValuestateHTMLCmtstateRCDATAstateAttrstateURLstateSrcsetstateJSstateJSDqStrstateJSSqStrstateJSTmplLitstateJSRegexpstateJSBlockCmtstateJSLineCmtstateJSHTMLOpenCmtstateJSHTMLCloseCmtstateCSSstateCSSDqStrstateCSSSqStrstateCSSDqURLstateCSSSqURLstateCSSURLstateCSSBlockCmtstateCSSLineCmtstateErrorstateMetaContentstateMetaContentURLstateDead" -var _state_index = [...]uint16{0, 9, 17, 30, 44, 60, 72, 83, 92, 100, 111, 118, 130, 142, 156, 169, 184, 198, 216, 235, 243, 256, 269, 282, 295, 306, 322, 337, 347, 356} +var _state_index = [...]uint16{0, 9, 17, 30, 44, 60, 72, 83, 92, 100, 111, 118, 130, 142, 156, 169, 184, 198, 216, 235, 243, 256, 269, 282, 295, 306, 322, 337, 347, 363, 382, 391} func (i state) String() string { if i >= state(len(_state_index)-1) { -- cgit v1.3