Secuno
ENNL
Book demo

CVE-2026-73552

Envoyproxy Envoy vulnerability

7.5 HIGHPublic exploitEPSS 0.47%
  1. Published21 Sept 2026

Description

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 HTTP RBAC accepts RFC-valid opaque header bytes but evaluates safe_regex values with RE2's UTF-8 subject semantics. A downstream client can preserve a prohibited marker and add an unrelated obs-text octet, causing RE2::FullMatch to return false and a negative RBAC policy to treat the invalid subject as an ordinary no-match. A byte-oriented route matcher can still observe the marker, allowing the request to reach a route intended to be denied. The relevant scope boundary is that plain positive ALLOW regexes normally fail closed, and exact, prefix, suffix, and contains matchers are not shown to have this subject-domain failure. This issue is fixed in versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityNone
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected products

Envoyproxy Envoy≥ 1.37.0 < 1.37.6 · ≥ 1.38.0 < 1.38.4 · ≥ 1.39.0 < 1.39.1 · < 1.36.10

Remediation

Fixed in
Envoyproxy Envoy≥ 1.37.6

References

Related CVEs

Recent high-severity vulnerabilities sharing a weakness type.

CVE-2026-843178.8
Nginx UI is a web user interface for the Nginx web server. Prior to 2.4.1,…
CVE-2026-843168.8
Nginx UI is a web user interface for the Nginx web server. Prior to 2.4.1,…
CVE-2026-571438.8
PraisonAI is a multi-agent teams system. Prior to praisonaiagents 1.6.62,…
CVE-2026-1034138.8
Improper input validation vulnerability in Apache Camel Karavan. When a deployment…
CVE-2026-764688.2
As part of Cisco's ongoing commitment to proactive security and product quality, the…
CVE-2026-764568.6
As part of Cisco's ongoing commitment to proactive security and product quality, the…

Frequently asked

Is CVE-2026-73552 being actively exploited?

CVE-2026-73552 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.47%.

How severe is CVE-2026-73552?

CVE-2026-73552 has a CVSS 3.1 base score of 7.5, rated high. EPSS estimates a 0.47% probability of exploitation.

Which products are affected by CVE-2026-73552?

Affected products include Envoyproxy Envoy.

How do I fix CVE-2026-73552?

Upgrade affected software to a fixed version, for example Envoyproxy Envoy 1.37.6 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-73552 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

See how prioritisation worksBook a demo

Get Patch this first every Monday

Five vulnerabilities that matter this week, ranked on real exploitation. Plain language, one email, no spam.

You can unsubscribe with one click from every issue. We handle your details as described in our privacy policy.

Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.