What is CVE-2026-73547?

CVE-2026-73547 is Envoy ext_authz: request `:path` pseudoheader dereferenced w/o null check. The supplied enrichment data classifies it as Memory Corruption mapped to CWE-20 Improper Input Validation; CWE-476 NULL Pointer Dereference.

Which versions are affected?

Affected product and version evidence is listed in the product table above. Current public advisories should be checked for exact version scope before patch targeting is finalized.

Is there active exploitation?

Active exploitation is not confirmed from current sources for CVE-2026-73547. If exploitation is not confirmed from current sources, teams should document that status and continue monitoring KEV, vendor, and telemetry updates.

No. CVE-2026-73547 is not listed in CISA KEV in the supplied enrichment data. KEV status should be monitored because it can change after initial disclosure or after exploitation becomes publicly confirmed.

Is there a public exploit?

A public PoC is not confirmed from current sources for CVE-2026-73547. Public exploit or PoC availability should raise triage priority, especially for exposed or business-critical systems.

How can defenders detect it?

Start with web/proxy/WAF logs, application logs, network IDS/IPS where available. Look for vulnerability-class behavior, product errors, suspicious authentication events, exploit probes, and abnormal process activity based only on evidence that applies to the affected product.

How should teams prioritize it?

Prioritize CVE-2026-73547 using CVSS 7.5, EPSS 0%, KEV status, public PoC status, and asset exposure. Internet-facing, privileged, or business-critical deployments should be handled first.

Are workarounds available?

The supplied mitigation guidance says to apply vendor patches and restrict external exposure until fixed. Fixed-version evidence is listed in the mitigation section above.

Which threat actors are linked publicly?

No public threat actor linkage is confirmed from current sources. Do not attribute exploitation to a threat actor unless the source evidence explicitly supports that linkage.

What should be done in the next 24 hours?

Identify exposed assets running affected vendor/product/version combinations. Prioritize based on EPSS, PoC availability, and external exposure. Search available logs for exploit probes, errors, authentication anomalies, or suspicious child processes matching the vulnerability class. Open remediation tickets with affected assets, owners, evidence status, and detection coverage so decisions are traceable.

highMemory Corruption

CVE-2026-73547

CVE-2026-73547 — Envoy ext_authz: request `:path` pseudoheader dereferenced w/o null check

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 ext_authz filter assumes that a request contains a :path pseudoheader when applying query_parameters_to_set or query_parameters_to_remove from an authorization response. A path-less CONNECT request makes request_headers_->Path() return null, and Filter::onComplete dereferences that pointer while parsing the query string. An unauthenticated downstream client can crash the Envoy process when the filter and authorization response use query-parameter mutation. The relevant scope boundary is that the deployment must accept path-less CONNECT and configure ext_authz query-parameter mutation. This issue is fixed in versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1.

Published Sep 21, 2026Updated Sep 21, 2026Sources: NVD, envoyproxy (CNA), GitHub, Red Hat (VEX), SOCRadar CTI

Triage

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

Exploitation

Unreported

no source claims exploitation

EPSS

ahead of 0% of scored CVEs

Affects

envoyproxy

4 products listed

CVSS base

7.5

high

Remediation

The vendor's own words where we have them.

Upgrade envoy to a fixed release. Apply vendor patches per advisory and restrict external exposure of the affected component until patched.

Red Hat VEX · CVE-2026-73547

fixed20affected0not affected105

vendor_fix: See Red Hat OpenShift Service Mesh 3.0.15 documentation at https://docs.redhat.com/en/documentation/red_hat_openshift_service_mesh/3.0

vendor_fix: See Red Hat OpenShift Service Mesh 3.1.12 documentation at https://docs.redhat.com/en/documentation/red_hat_openshift_service_mesh/3.1

vendor_fix: See Red Hat OpenShift Service Mesh 3.2.9 documentation at https://docs.redhat.com/en/documentation/red_hat_openshift_service_mesh/3.2

First 24 hours

Ordered from the record's own fields — exposure first, because you cannot patch what you have not found.

Identify exposed assets running affected vendor/product/version combinations.
Prioritize based on EPSS, PoC availability, and external exposure.
Search available logs for exploit probes, errors, authentication anomalies, or suspicious child processes matching the vulnerability class.

Affected scope

Vendor, product and version as the advisories word them.

Vendor	Product	Versions	Status
envoyproxy	envoy	< 1.36.10	Vulnerable
envoyproxy	envoy	>= 1.37.0, < 1.37.6	Vulnerable
envoyproxy	envoy	>= 1.38.0, < 1.38.4	Vulnerable
envoyproxy	envoy	>= 1.39.0, < 1.39.1	Vulnerable

Attack characteristics

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

Availability

High

Confidentiality

None

Integrity

None

Scope

Unchanged

Attack Complexity

Low

Attack Vector

Network

Privileges Req

None

User Interaction

None

Every base score collected

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

Score	Version	Severity	Expl.	Impact	Source
7.5	CVSS 3.1	high	3.9	3.6	GitHub (CNA), envoyproxy (CNA), Red Hat (VEX)

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

What this weakness leads to

MITRE's own consequences and mitigations for the weakness class — the authority's wording, not guidance derived from the CVSS vector.

MITRE

CWE-476 · NULL Pointer Dereference

DoS: Crash, Exit, or Restart
Execute Unauthorized Code or Commands
Read Memory
Modify Memory

Mitigation: If all pointers that could have been modified are sanity-checked previous to use, nearly all NULL pointer dereferences can be prevented.

CWE-20 · Improper Input Validation

DoS: Crash, Exit, or Restart
DoS: Resource Consumption (CPU)
DoS: Resource Consumption (Memory)
Read Memory

Mitigation: Consider using language-theoretic security (LangSec) techniques that characterize inputs using a formal language and build recognizers for that language. This effectively requires parsing to be a distinct layer that effectively enforces a boundary between raw input and internal data representations, instead of allowing parser code to be scattered throughout the program, where it could be subject to errors or inconsistencies that create weaknesses. [REF-1109] [REF-1110] [REF-1111]

Weakness & attack patterns

CWE-20Improper Input Validation
CWE-476NULL Pointer Dereference

Attack patterns reported against this CVE. The ATT&CK techniques below are inferred from its weakness class.

CAPEC-67 · String Format Overflow in syslog()CAPEC-261 · Fuzzing for garnering other adjacent user/sensitive dataCAPEC-182 · Flash InjectionCAPEC-267 · Leverage Alternate EncodingCAPEC-71 · Using Unicode Encoding to Bypass Validation LogicCAPEC-46 · Overflow Variables and TagsCAPEC-83 · XPath InjectionCAPEC-22 · Exploiting Trust in ClientCAPEC-3 · Using Leading 'Ghost' Character Sequences to Bypass Input FiltersCAPEC-13 · Subverting Environment Variable ValuesCAPEC-8 · Buffer Overflow in an API CallCAPEC-250 · XML Injection

T1562.003Impair Defenses: Impair Command History Logging
T1574.006Hijack Execution Flow: Dynamic Linker Hijacking
T1574.007Hijack Execution Flow: Path Interception by PATH Environment Variable

Detection

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

Prioritize edge telemetry for network-reachable envoy.

web/proxy/WAF logsapplication logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first — with the readings a source repeats on a schedule counted underneath rather than listed.

2026
Added · CVSS 3.1 7.5 (AV:N)
Sep 21, 2026 · NVD
Initial · CVE published
Sep 21, 2026 · NVD
CVE published by MITRE.
Sep 21, 2026 · SOCRadar CTI

References

18 on the record

github.com/envoyproxy/envoy/commit/064af2e61d0d1c421490d9e3e6e643c5d117ffe4
Exploit, Third Party Advisory, Mitre
github.com/envoyproxy/envoy/commit/5f3b8e9b2b8a787a63202d35bb38820f3e9271fe
Exploit, Third Party Advisory, Mitre
github.com/envoyproxy/envoy/commit/838f8ffd9d7b5217682a22ee33470d4c7afb7e98
Exploit, Third Party Advisory, Mitre
github.com/envoyproxy/envoy/commit/c3170d7c747e51bb8254378ea89afc03d3e71929
Exploit, Third Party Advisory, Mitre
github.com/envoyproxy/envoy/releases/tag/v1.36.10
Exploit, Third Party Advisory, Mitre
github.com/envoyproxy/envoy/releases/tag/v1.37.6
Exploit, Third Party Advisory, Mitre
github.com/envoyproxy/envoy/releases/tag/v1.38.4
Exploit, Third Party Advisory, Mitre
github.com/envoyproxy/envoy/releases/tag/v1.39.1
Exploit, Third Party Advisory, Mitre

Elsewhere on this site

envoyproxyevery CVE for this vendor
Memory Corruptionsame class
CWE-20other pages naming this weakness

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 record1

What should defenders know first?

CVE-2026-73547 is Envoy ext_authz: request `:path` pseudoheader dereferenced w/o null check, a high vulnerability affecting envoy from envoyproxy. The current evidence does not list it in CISA KEV, and the exploit status is: Active exploitation is not confirmed from current sources for CVE-2026-73547. Public exploit evidence is: A public PoC is not confirmed from current sources for CVE-2026-73547. The affected-version evidence is listed in the key facts and affected products tables. Defenders should first verify whether exposed or business-critical assets run those versions, then apply vendor patches or mitigations, restrict reachable attack surface, and preserve logs for detection review. CVSS 7.5 describes technical severity, while EPSS 0% helps estimate near-term exploit likelihood; neither replaces asset context. Unknown fields should remain explicit in tickets, and threat actor, IOC, victimology, or payload claims should not be added unless a cited source supports them. Monitor CISA KEV, vendor advisories, NVD changes, public PoC repositories, and internal telemetry for update triggers.