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CVE-2026-73552Suited to automated attack · CISA

Envoy: HTTP RBAC safe_regex can fail open on RFC-valid obs-text header values

CVSS score

7.5

EPSS probability

%0.5

Risk score

0.0

Published

27 d ago

OverviewPublic Exploits (0)NewsroomVulnerability Timeline
Official patch verified

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Impact on My Inventory

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Vulnerability description

DayBreach CVE AI Research

CVE-2026-73552 has vendor, distribution, patch and security-source records on file. We can compare them and prepare an explanation linked to the evidence.

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.

IMPACT: Affected Products and Software

Affected Products

The following products are affected by CVE-2026-73552 vulnerability. Where our threat engine knows the exact affected versions, they are listed below.

IDVENDORPRODUCTACTION
1envoyproxyenvoy View
2envoyproxyenvoy View
3envoyproxyenvoy View
4envoyproxyenvoy View
5envoyproxyenvoy View
Total affected vendors: 1|Products: 5

RED HAT CSAF/VEX: Product Impact Check

Red Hat has not yet published a CSAF/VEX impact record for this CVE. This does not mean “not affected”.

SCORING: CVSS from Multiple Sources

CVSS Scores

The Common Vulnerability Scoring System is a standardised framework for assessing the severity of vulnerabilities in software and systems. We collect and display CVSS scores from several sources for each CVE.

SCOREVERSIONSEVERITYVECTORSOURCE
7.5CVSS V3_1HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:NCVE CNA
7.5CVSS V31HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:NNVD

Patch and Remediation Guide

Solution & Remediation Advisory

Patch verified

4 doğrulanmış yama veya düzeltilmiş sürüm kanıtı bulundu.

nvd

NVD tarafından Patch olarak etiketlenmiş referans

Open source
nvd

NVD tarafından Patch olarak etiketlenmiş referans

Open source
nvd

NVD tarafından Patch olarak etiketlenmiş referans

Open source
nvd

NVD tarafından Patch olarak etiketlenmiş referans

Open source
Confirm the affected product and version against the source evidence above.
Restrict access to internet-facing services and apply network segmentation.
Apply the official update named in the evidence only to the matching product and version.
Monitor server logs and network endpoints for signs of anomalous execution.

Public exploit and active exploitation status

Verified exploit intelligence

No verified public PoC, exploit repository or Metasploit module has been found for this CVE yet.

Weakness Classification and Attack Patterns (CWE & CAPEC)

CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-73552 is associated with the following CWEs:

CWE-20: Improper Input Validation

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-73552 weaknesses.

CAPEC-66: SQL InjectionCAPEC-126: Path TraversalCAPEC-28: OS Command Injection

Attack Vector and Accessibility

ExposureAğ üzerinden
PermissionsGerekmiyor
UserGerekmiyor

Official Sources and Advisories

https://github.com/envoyproxy/envoy/security/advisories/GHSA-23xh-2qxr-3xv8vendor-advisoryhttps://github.com/envoyproxy/envoy/commit/5650cb9770d4420ec2bcbed8b90be06f564ecc07vendor-advisoryhttps://github.com/envoyproxy/envoy/commit/7d1dee5dda66434d84437cc5c85153aa03955e26vendor-advisoryhttps://github.com/envoyproxy/envoy/commit/c2b9a19dc081f03be6a9b4ca932673e5e7a33d18vendor-advisoryhttps://github.com/envoyproxy/envoy/commit/f3726765f3a12ddc76dcb52c0b79bec3d95ced1cvendor-advisoryhttps://github.com/envoyproxy/envoy/releases/tag/v1.36.10vendor-advisoryhttps://github.com/envoyproxy/envoy/releases/tag/v1.37.6vendor-advisoryhttps://github.com/envoyproxy/envoy/releases/tag/v1.38.4vendor-advisoryhttps://github.com/envoyproxy/envoy/releases/tag/v1.39.1vendor-advisory

CVSS Vector Radar Chart

7.5 / 10
Attack VectorNetworkComplexityLowPrivilegesNoneUser Interact.NoneConfidentialityLowIntegrityNoneAvailabilityNone

Vulnerability Scoring Details

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredNone required
User InteractionNone required
Confidentiality (Gizlilik)Low
Integrity (Bütünlük)None
Availability (Erişilebilirlik)None

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Weakness Type (CWE & CAPEC)

CWE-20

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