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Fencer Vulns
medium 6.1

CVE-2026-118652 json

Echo: Reflected Cross-Site Scripting (XSS) via unsanitized JSONP callback in Context.JSONP / Context.JSONPBlob

published 2026-10-28 11 d ago modified 2026-11-05 3 d ago also GHSA-h9g5-28mm-hx3g , GO-2026-6876 , EUVD-2026-112408

cvss
6.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 15%
public exploits
0
none known

Summary

Echo is a Go web framework. Prior to 4.16.0 and 5.4.0, Context.JSONP and Context.JSONPBlob concatenate an unvalidated callback value into a JavaScript response. A route that passes attacker-controlled input as the callback can return executable script syntax, allowing reflected cross-site scripting when a user loads the crafted response. The vulnerable jsonPBlob path performs no callback validation or escaping, and exploitation requires an application route that exposes attacker control over the callback argument. This issue is fixed in 4.16.0 and 5.4.0.

Patch / fix

  • go github.com/labstack/echo/v5 5.4.0
  • go github.com/labstack/echo/v4 4.16.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-118652 updated cvss 6.1

github.com/labstack/echo: Echo: Reflected Cross-Site Scripting via unvalidated JSONP callback

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
5 d ago

Exploit prediction

0.24% chance of exploitation in the next 30 days, higher than 15% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/labstack/echo/security/advisories/GHSA-h9g5-28mm-hx3g referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
GitHub 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Affected packages

ecosystem package affected fixed in
go github.com/labstack/echo/v5
<5.4.0
5.4.0
go github.com/labstack/echo/v4
<4.16.0
4.16.0

Affected products

  • labstack echo

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.