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Public proof of conceptFix availableAwaiting NVD analysis

CVE-2026-118652

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

A public proof of concept exists; no exploitation attested.

  • Published2026-10-28
  • Fixed in4.16.0
  • WeaknessCWE-79

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

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.

Timeline

dates in UTC
  1. 2026-10-2819:35CVE publishedCNA

Observed activity

isMalicious corpus · updated 2026-11-03 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-118652?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-118652?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

OSV
labstack/echo
BranchAffectedFixed in
4.16< 4.16.04.16.0
labstack/echo
BranchAffectedFixed in
5.4< 5.4.05.4.0

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Products declared by the CNA1 product

As GitHub_M, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

  • labstack echo
    Affected
    • = < 4.16.0no fix stated
    • = >= 5.0.0, < 5.4.0no fix stated

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2026-10-28

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • github.com/labstack/echo/v4Echo:Goall versions · fixed in 4.16.0
  • golang-github-labstack-echoUbuntu:26.10all versions · no fixed version listed
  • golang-github-labstack-echoUbuntu:26.04:LTSall versions · no fixed version listed
  • golang-github-labstack-echoUbuntu:24.04:LTSall versions · no fixed version listed
  • golang-github-labstack-echoUbuntu:22.04:LTSall versions · no fixed version listedand 2 other packages
  • golang-github-labstack-echoDebian:14all versions · no fixed version listed
  • golang-github-labstack-echoDebian:13all versions · no fixed version listed
  • golang-github-labstack-echoDebian:12all versions · no fixed version listed

1 more package range on OSV.dev

Full record on NVD

Fix

  1. Update labstack/echo to 4.16.0

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub
Metasploit modules
none listed
Metasploit Framework

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Published
2026-10-28
Last Modified
2026-11-03
NVD status
Undergoing Analysis
GitHub Advisory
GHSA-h9g5-28mm-hx3g

Frequently asked questions

What is CVE-2026-118652?

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.

Is CVE-2026-118652 actively exploited?

A proof-of-concept exploit exists for CVE-2026-118652, but active exploitation has not been confirmed at this time.

What is the CVSS score for CVE-2026-118652?

CVE-2026-118652 has a CVSS v3 base score of 6.1 (MEDIUM severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

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Sources for this record