You can also see the bug by typing NextAction<today-1 in the crbug.com query box and clicking Search.

I was able to repro the issue in the latest Canary 58.0.2991.0 on Mac OS. It seems to be a request failure after the response is received. I captured the net logs dump, and looking at the the original request, we seemed to have no problem. However, those URLRequests to bugs.chromium.org/static/js/... are aborted. 

Deleted: net-internals-log (5).json 252 KB

net-internals-log (5).json 252 KB View Download

+mkwst who has been making changes to XSS auditor, afair. Most likely not a networking issue.

Looks like a false-positive due to some strange markup that monorail generates (I think the unquoted empty attribute in `<form id='bulkremoveissues' method="POST" action=>` is confusing the Auditor).

Filed https://bugs.chromium.org/p/monorail/issues/detail?id=2142 against Monorail, as that markup seems broken, but we should probably tune the auditor as well. Tom, would you mind taking a look?

(Removing the network label since this is originating from Blink.)

I just hit this too (and then was frustrated that my queries attempting to find bugs modified recently mentioning ERR_BLOCKED_BY_XSS_AUDITOR weren't working).  This is a recent regression (Chrome 55 seems fine), right?  Seems potentially urgent - marking P1 release blocking proactively.

Let's get a bisect to see what CL broke this.

For the record here's one URL that triggers this error in Chrome 57 but works in Chrome 55:
https://bugs.chromium.org/p/chromium/issues/list?can=1&q=touch-action+cc%3Arbyers+Status%3AWontFix+closed>today-60

I'm not sure if BLOCKED_BY_XSS_AUDITOR shows up in net error codes (which are only logged if the request does not complete).

It would be a good idea to ensure xss monitor has metrics so we can properly detect significance of issues like this.

I was ready to up the priority but I suppose I can do triage on a stable release.

For the record, the problem is not the ">", it's the length of the string combined with certain characters.

For example, this works
Component:Blink>Paint,Blink>Paint>Invalidation status=Unconfirmed,Untriaged

but this does not

Component:Blink>Paint,Blink>Paint>Invalidation status=Unconfirmed,Untriaged -has:NextACtion

To be precise, it's not just the ">", it's the ">" combined with the length or something else.

I deployed a new version of Monorail that fixes the <form action=> markup.  The original link in this issue description now works on Chrome 58.0.2993.0 canary 64-bit on mac.

First off, you need one of [><"'] in the URL or the auditor doesn't even run.
 
From the example in the original description, we may matching
|action=| in the page against |NextAction<Today|, which should have failed since we're supposed to include the equals sign and the value (in this case empty).

For unquoted attributes at the end of a tag, we've been silently losing the equals sign for comparison, matching the name only, and then re-writing this as name=, which changes nothing until blocking was enabled by default.

CL at https://codereview.chromium.org/2663433002/

Its working fine now on Ubuntu 14.04,Mac 10.12.2 and Win 10 using 57.0.2987.8,55.0.2883.87/95 and canary 58.0.2993.0.

Removed the Needs-Bisect and RealeaseBloack-stable labels for now, please ad again if its reproducible again.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/92e34fe0db746b9a2d1112a942410124bfaf6259

commit 92e34fe0db746b9a2d1112a942410124bfaf6259
Author: tsepez <tsepez@chromium.org>
Date: Fri Jan 27 21:11:36 2017

XSSAuditor: Include equals-sign for final unquoted empty attributes.

This will help reduce the false positive rate.

BUG= 683798 

Review-Url: https://codereview.chromium.org/2663433002
Cr-Commit-Position: refs/heads/master@{#446768}

[add] https://crrev.com/92e34fe0db746b9a2d1112a942410124bfaf6259/third_party/WebKit/LayoutTests/http/tests/security/xssAuditor/form-action-unquoted-empty-expected.txt
[add] https://crrev.com/92e34fe0db746b9a2d1112a942410124bfaf6259/third_party/WebKit/LayoutTests/http/tests/security/xssAuditor/form-action-unquoted-empty.html
[add] https://crrev.com/92e34fe0db746b9a2d1112a942410124bfaf6259/third_party/WebKit/LayoutTests/http/tests/security/xssAuditor/resources/echo-form-action-unquoted.pl
[modify] https://crrev.com/92e34fe0db746b9a2d1112a942410124bfaf6259/third_party/WebKit/Source/core/html/parser/XSSAuditor.cpp