CVE-2026-39823
Bypass of meta content URL escaping causes XSS in html/template
Description
CVE-2026-27142 fixed a vulnerability in which URLs were not correctly escaped inside of a <meta> tag's <content> attribute. If the URL content were to insert ASCII whitespaces around the '=' rune inside of the <content> attribute, the escaper would fail to similarly escape it, leading to XSS.
INFO
Published Date :
May 7, 2026, 8:16 p.m.
Last Modified :
May 7, 2026, 8:38 p.m.
Remotely Exploit :
No
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-39823
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
Solution
- Update the escaper to handle ASCII whitespaces correctly.
- Sanitize all URL inputs before attribute insertion.
- Validate URL content for malicious patterns.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-39823.
| URL | Resource |
|---|---|
| https://go.dev/cl/769920 | |
| https://go.dev/issue/78913 | |
| https://groups.google.com/g/golang-announce/c/qcCIEXso47M | |
| https://pkg.go.dev/vuln/GO-2026-4982 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-39823 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-39823
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-39823 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-39823 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by [email protected]
May. 07, 2026
Action Type Old Value New Value Added Description CVE-2026-27142 fixed a vulnerability in which URLs were not correctly escaped inside of a <meta> tag's <content> attribute. If the URL content were to insert ASCII whitespaces around the '=' rune inside of the <content> attribute, the escaper would fail to similarly escape it, leading to XSS. Added Reference https://go.dev/cl/769920 Added Reference https://go.dev/issue/78913 Added Reference https://groups.google.com/g/golang-announce/c/qcCIEXso47M Added Reference https://pkg.go.dev/vuln/GO-2026-4982