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VulnerabilityPublished

CVE-2026-27136: golang.org/x/net/html · Cross-site Scripting

Affects golang.org/x/net/htmlSource CVE Database V5

0
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Not known to be exploited · CVSS 6.1 Medium : upgrade to 0.55.0 when convenient.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score
6.1Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 12% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 0.55.0
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 22 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Upgrade golang.org/x/net/html to 0.55.0.

Affected software

ProductAffectedFixed in
golang.org/x/netgolang.org/x/net/htmlAffected
  • <0.55.0
Fixed in
  • 0.55.0
Gogolang.org/x/net/htmlpkg:golang/golang.org/x/net/htmlOther threatsAffected
  • =0
Fixed in–
Gogolang.org/x/net/htmlpkg:golang/golang.org/x/net/htmlOther threatsAffected
  • <0.55.0
Fixed in
  • 0.55.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

If you cannot patch yet, users should exercise caution when using golang.org/x/net/html to sanitize untrusted HTML input and consider additional layers of input validation or sanitization outside this package.

Description

CVE-2026-27136 is a medium severity vulnerability in the golang.org/x/net/html package where parsing arbitrary HTML and rendering it using the Render function can produce an unexpected HTML tree. This behavior may be exploited to perform cross-site scripting (XSS) attacks in applications that rely on this package to sanitize input HTML before rendering. The vulnerability involves improper neutralization of input during web page generation (CWE-79).

References

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