Vulnerability · Published May 7, 2026 · Assigned by Go
CVE-2026-39823Bypass of meta content URL escaping causes XSS in html/template
Medium 6.1
In plain English
A medium-severity security flaw in html/template from Go standard library. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 24% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)6.1Medium
Exploit odds (30 days)0.3%top 75.5% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:8 | delve | 1.25.2-1.module_el8.10.0+4074+24330916 | ALSA-2026:22112 |
| AlmaLinux:8 | go-toolset | 1.25.10-1.module_el8.10.0+4187+c45165c4 | ALSA-2026:22112 |
| AlmaLinux:9 | go-toolset | 1.26.3-1.el9_8 | ALSA-2026:22121 |
| AlmaLinux:8 | golang | 1.25.10-1.module_el8.10.0+4187+c45165c4 | ALSA-2026:22112 |
| AlmaLinux:9 | golang | 1.26.3-1.el9_8 | ALSA-2026:22121 |
| AlmaLinux:8 | golang-bin | 1.25.10-1.module_el8.10.0+4187+c45165c4 | ALSA-2026:22112 |
| AlmaLinux:9 | golang-bin | 1.26.3-1.el9_8 | ALSA-2026:22121 |
| AlmaLinux:8 | golang-docs | 1.25.10-1.module_el8.10.0+4187+c45165c4 | ALSA-2026:22112 |
| AlmaLinux:9 | golang-docs | 1.26.3-1.el9_8 | ALSA-2026:22121 |
| AlmaLinux:8 | golang-misc | 1.25.10-1.module_el8.10.0+4187+c45165c4 | ALSA-2026:22112 |
| AlmaLinux:9 | golang-misc | 1.26.3-1.el9_8 | ALSA-2026:22121 |
| AlmaLinux:8 | golang-race | 1.25.10-1.module_el8.10.0+4187+c45165c4 | ALSA-2026:22112 |
| AlmaLinux:9 | golang-race | 1.26.3-1.el9_8 | ALSA-2026:22121 |
| AlmaLinux:8 | golang-src | 1.25.10-1.module_el8.10.0+4187+c45165c4 | ALSA-2026:22112 |
| AlmaLinux:9 | golang-src | 1.26.3-1.el9_8 | ALSA-2026:22121 |
| AlmaLinux:8 | golang-tests | 1.25.10-1.module_el8.10.0+4187+c45165c4 | ALSA-2026:22112 |
| AlmaLinux:9 | golang-tests | 1.26.3-1.el9_8 | ALSA-2026:22121 |
| Alpine:v3.23 | go | 1.25.10-r0 | ALPINE-CVE-2026-39823 |
| Alpine:v3.24 | go | 1.26.3-r0 | ALPINE-CVE-2026-39823 |
| Alpine:v3.24 | rclone | 1.74.1-r0 | ALPINE-CVE-2026-39823 |
| Debian:12 | golang-1.19 | no fix listed | DEBIAN-CVE-2026-39823 |
| Debian:13 | golang-1.24 | no fix listed | DEBIAN-CVE-2026-39823 |
| Debian:14 | golang-1.26 | 1.26.3-1 | DEBIAN-CVE-2026-39823 |
| Go | stdlib | 1.25.10, 1.26.3 | GO-2026-4982 |
| Rocky Linux:8 | delve | 0:1.25.2-1.module+el8.10.0+40035+ee0a7047 | RLSA-2026:22112 |
| Rocky Linux:10 | golang | 0:1.26.3-4.el10_2 | RLSA-2026:22120 |
| Rocky Linux:8 | golang | 0:1.25.10-1.module+el8.10.0+40200+0fd0f175 | RLSA-2026:22112 |
| Rocky Linux:9 | golang | 0:1.26.3-1.el9_8 | RLSA-2026:22121 |
| Ubuntu:22.04:LTS | golang-1.17 | no fix listed | UBUNTU-CVE-2026-39823 |
| Ubuntu:22.04:LTS | golang-1.18 | no fix listed | UBUNTU-CVE-2026-39823 |
| Ubuntu:22.04:LTS | golang-1.20 | no fix listed | UBUNTU-CVE-2026-39823 |
| Ubuntu:22.04:LTS | golang-1.21 | no fix listed | UBUNTU-CVE-2026-39823 |
| Ubuntu:24.04:LTS | golang-1.21 | no fix listed | UBUNTU-CVE-2026-39823 |
| Ubuntu:22.04:LTS | golang-1.22 | no fix listed | UBUNTU-CVE-2026-39823 |
| Ubuntu:24.04:LTS | golang-1.22 | no fix listed | UBUNTU-CVE-2026-39823 |
| Ubuntu:22.04:LTS | golang-1.23 | no fix listed | UBUNTU-CVE-2026-39823 |
| Ubuntu:24.04:LTS | golang-1.23 | no fix listed | UBUNTU-CVE-2026-39823 |
| Ubuntu:25.10 | golang-1.23 | no fix listed | UBUNTU-CVE-2026-39823 |
| Ubuntu:26.04:LTS | golang-1.23 | no fix listed | UBUNTU-CVE-2026-39823 |
| Ubuntu:22.04:LTS | golang-1.24 | no fix listed | UBUNTU-CVE-2026-39823 |
| Ubuntu:24.04:LTS | golang-1.24 | no fix listed | UBUNTU-CVE-2026-39823 |
| Ubuntu:25.10 | golang-1.24 | no fix listed | UBUNTU-CVE-2026-39823 |
| Ubuntu:26.04:LTS | golang-1.24 | no fix listed | UBUNTU-CVE-2026-39823 |
| Ubuntu:22.04:LTS | golang-1.25 | no fix listed | UBUNTU-CVE-2026-39823 |
| Ubuntu:24.04:LTS | golang-1.25 | no fix listed | UBUNTU-CVE-2026-39823 |
| Ubuntu:25.10 | golang-1.25 | no fix listed | UBUNTU-CVE-2026-39823 |
| Ubuntu:26.04:LTS | golang-1.25 | no fix listed | UBUNTU-CVE-2026-39823 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Go standard library | html/template | 0 – before 1.25.101.26.0-0 – before 1.26.3 |