CVE Intelligence
High Cross-site scripting exploit reference

CVE-2026-73546 — Envoy: Stored XSS in Admin Stats Interface (/stats?format=html)

Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1, Envoy's /stats?format=html admin endpoint uses StatsHtmlRender, which sanitizes string statistic values but emits statistic names without HTML encoding. A data-plane component such as grpc_stats with stats_for_all_methods enabled can incorporate attacker-controlled path segments into cached dynamic statistic names. When an operator views the HTML stats page, the stored name can execute script with the admin interface's origin and issue privileged same-origin requests. The relevant scope boundary is that the admin interface must be browser-accessible and an enabled component must persist attacker-influenced text in statistic names. This issue is fixed in versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1.

Published Sep 21, 2026 · Updated Oct 15, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: GitHub_M

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 0.6% (30-day exploitation probability)+7
  • Technical severity (high)+6
  • CISA SSVC: exploitation "poc"+5

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
0.62%
ahead of 48% of scored CVEs · Oct 15, 2026
Affects
Envoyproxy
Envoy
CVSS base
7.4
High · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation
Proof of concept
none · proof-of-concept · active
Automatable
No
can an attacker script the kill-chain steps
Technical impact
Total
partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

  • Documented patch — github.com (NIST National Vulnerability Database)
  • Documented patch — github.com (NIST National Vulnerability Database)
  • Documented patch — github.com (NIST National Vulnerability Database)
  • Documented patch — github.com (NIST National Vulnerability Database)

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Envoyproxy Envoy).
  2. The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
  3. Apply the fixed version or the patch documented under Remediation.
  4. Search available logs for exploit probes matching the vulnerability class (cross-site scripting), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Envoyproxy Envoy < 1.36.10≥ 1.37.0 and < 1.37.6≥ 1.38.0 and < 1.38.4≥ 1.39.0 and < 1.39.1 Vulnerable NIST National Vulnerability Database
Envoyproxy Envoy version < 1.36.10version >= 1.37.0, < 1.37.6version >= 1.38.0, < 1.38.4version >= 1.39.0, < 1.39.1 Vulnerable CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
7.4 CVSS 3.1 High 2.2 5.2 security-advisories@github.com via NIST National Vulnerability Database
7.4 CVSS 3.1 High — — GitHub_M via CVE Program (cve.org) e CISA ADP
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N (score shown at the top: security-advisories@github.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-79 · Cross-site Scripting (XSS)

Other CVEs with this weakness →

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
  • Monitor CSP violation reports and script payloads in reflected parameters.
web/proxy/WAF logsnetwork IDS/IPSapplication logs

Timeline

What happened to this CVE, newest first.

  • 2026
  • Affected products added · envoyproxy/envoy
    Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
  • SSVC assessment updated
    Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 15, 2026
  • Fix documented
    Oct 15, 2026 · NIST National Vulnerability Database
  • CVSS changed · 7.4
    Oct 15, 2026 · NIST National Vulnerability Database
  • Source status changed · → Analyzed
    Oct 15, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 15, 2026 · NIST National Vulnerability Database
  • CVE published
    Sep 21, 2026 · GitHub_M

Source activity

Repeated readings are counted rather than listed.

  • 1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

9 on the record

Elsewhere on this site

Envoyproxy
every CVE for this vendor
Cross-site scripting
same class
CWE-79
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-73553 Envoy: RBAC Authorization Bypass via Path Parameters 24d
  • CVE-2026-73511 Envoy: Potential path-matching/authentication bypass when using Envoy in combination with a backend stripping per-segment path (matrix) parameters (e.g. Apache Tomcat) 24d
  • CVE-2026-73551 Envoy: Path normalization does not handle dot and dotdot segments with parameters 24d
  • CVE-2026-73549 Envoy - Incomplete fix for CVE-2026-26310: copyInternetAddressAndPort crashes on scoped IPv6 addresses in ORIGINAL_DST clusters 24d
  • CVE-2026-73552 Envoy: HTTP RBAC safe_regex can fail open on RFC-valid obs-text header values 24d
  • CVE-2026-73548 Envoy: Cross-user response poisoning via a generic (non-WebSocket) HTTP upgrade on Envoy's shared backend pool 24d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-73546 is "Envoy: Stored XSS in Admin Stats Interface (/stats?format=html)", rated High. It affects Envoy (Envoyproxy); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.4 describes technical severity. EPSS 0.62% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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