CVE-2026-39823 | Bypass of meta content URL escaping causes XSS in html/template

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.

Published: 2026-05-07 Last update: 2026-05-13 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-39823 is rated Low Risk (24.9/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.01%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-39823

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-08 — 0.01% —

Full EPSS history (1 record total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-39823

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.1 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 2.7 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2026-39823

GitHub Security Advisory for CVE-2026-39823

GHSA-2283-wf8c-rw8r · Severity: medium — CVE-2026-27142 fixed a vulnerability in which URLs were not correctly escaped inside of a <meta>...

OS Trackers for CVE-2026-39823

vendor priority summary link
debian not yet assigned CVE-2026-39823 not yet assigned priority: Debian including 5 source packages (golang-1.15, golang-1.19, golang-1.24, golang-1.25, golang-1.26), 7 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 4, open 3. https://security-tracker.debian.org/tracker/CVE-2026-39823
suse medium CVE-2026-39823 severity moderate: SUSE including 7 source package names (go, go-doc, …), 33 product×package rows across 14 product lines (SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS, SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS, … (14 product lines)): Known Not Affected 29, Fixed 4. https://www.suse.com/security/cve/CVE-2026-39823/
ubuntu medium CVE-2026-39823 medium priority: Ubuntu including 16 source packages (golang, golang-1.10, …), 98 status rows across 9 suites (bionic, focal, jammy, noble, questing, resolute, trusty, upstream, xenial): needs-triage 52, DNE 46. https://ubuntu.com/security/CVE-2026-39823

Affected software / configurations for CVE-2026-39823

Vendor Product Version Raw CPE
golang go < 1.25.10 cpe:2.3:a:golang:go:*:*:*:*:*:*:*:*
golang go >= 1.26.0, < 1.26.3 cpe:2.3:a:golang:go:*:*:*:*:*:*:*:*

References for CVE-2026-39823

cvelogic Threat Intelligence