Is CVE-2026-73552 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-73552 being exploited in the wild.

How severe is CVE-2026-73552?

High severity, with a CVSS score of 7.5, published 21 September 2026.

Which products and versions are affected?

Envoy before 1.36.10, 1.37.0-1.37.5, 1.38.0-1.38.3, 1.39.0.

Is there a fix for CVE-2026-73552?

A patch was published on 2026-08-26: Fix committed in versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-73552 attacked?

It is attacked over the network, in a hosted service.

Am I affected by CVE-2026-73552?

Check whether you run Envoy at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-73552: Envoy HTTP RBAC bypass via unsafe regex in headers

CVE-2026-73552 · Severity: high · CVSS 7.5 · Published 2026-09-21

Envoy is a widely-used network proxy that enforces access control policies on HTTP traffic. The vulnerability allows a malicious downstream client to bypass HTTP role-based access control (RBAC) policies by crafting specially-formed header bytes that exploit a regex evaluation flaw. An attacker can reach routes that should be denied by the RBAC policy, potentially leading to unauthorized access to protected services.

Technologies: Envoy. Vendors: Envoy.

Quick answers

Is CVE-2026-73552 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-73552 being exploited in the wild.
How severe is CVE-2026-73552?: High severity, with a CVSS score of 7.5, published 21 September 2026.
Which products and versions are affected?: Envoy before 1.36.10, 1.37.0-1.37.5, 1.38.0-1.38.3, 1.39.0.
Is there a fix for CVE-2026-73552?: A patch was published on 2026-08-26: Fix committed in versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-73552 attacked?: It is attacked over the network, in a hosted service.
Am I affected by CVE-2026-73552?: Check whether you run Envoy at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

The vulnerability exists in Envoy's HTTP RBAC implementation, which evaluates safe_regex policy expressions using RE2's UTF-8 subject semantics even though HTTP headers are Latin1-encoded bytes. An attacker can preserve a prohibited marker in the header and append an invalid obs-text octet, causing RE2::FullMatch to return false for negative RBAC policies while a byte-oriented route matcher still observes the marker. The fix switches safe_regex charset mode from UTF-8 to Latin1 to properly handle HTTP header bytes.

Affected products

Envoy Envoy before 1.36.10, 1.37.0-1.37.5, 1.38.0-1.38.3, 1.39.0

Timeline

2026-09-21: disclosed
2026-08-26: patched: Fix committed in versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1

References

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