What is the CVSS score of CVE-2026-48044?

CVE-2026-48044 has a CVSS 3.1 base score of 7.5 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. EPSS exploitation probability: 0.5%.

Which versions of Envoy are affected by CVE-2026-48044?

Envoy proxy versions 1.23.0 through 1.35.10, 1.36.6, 1.37.2, and 1.38.0 contain a remote denial-of-service vulnerability that can crash proxy instances when zstd decompression is enabled.. A patch is available.

How to fix or mitigate CVE-2026-48044?

Within 24 hours: Identify all Envoy deployments running affected versions; audit which instances have zstd decompression enabled and classify by business criticality. Within 7 days: Disable zstd decompression where operationally feasible; for systems requiring zstd, implement network-level access controls restricting inbound traffic to Envoy endpoints, and deploy monitoring for abnormal memory usage and proxy crashes. Within 30 days: Establish continuous monitoring of Envoy security advisories for patch availability; develop and test upgrade pathways to non-vulnerable versions; architect failover or load-balancing strategies for critical Envoy instances that cannot be rapidly patched.

Envoy CVE-2026-48044

EUVD-2026-39820 HIGH

Improper Handling of Highly Compressed Data (Data Amplification) (CWE-409)

2026-06-26 GitHub_M

Denial Of Service Red Hat Envoy Suse Envoyproxy

7.5

CVSS 3.1 · Vendor: GitHub_M

Severity by source

Vendor (GitHub_M) PRIMARY

7.5 HIGH

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

vuln.today AI

7.5 HIGH

Remote, unauthenticated, low-complexity payload causes proxy OOM with availability-only impact; no confidentiality or integrity loss, and scope remains unchanged within the process.

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

4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

SUSE

HIGH

qualitative

Red Hat

7.5 HIGH

qualitative

Primary rating from Vendor (GitHub_M).

CVSS VectorVendor: GitHub_M

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Lifecycle Timeline

Patch available

Jun 26, 2026 - 19:02 EUVD

Analysis Generated

Jun 26, 2026 - 18:32 vuln.today

DescriptionCVE.org

Envoy is an open source edge and service proxy designed for cloud-native applications. From 1.23.0 until 1.35.11, 1.36.7, 1.37.3, and 1.38.1, a vulnerability has been identified in Envoy's zstd decompressor implementation (ZstdDecompressorImpl). When zstd decompression is enabled, processing a specially crafted, highly compressed zstd payload can lead to massive memory allocation. An attacker can exploit this to cause severe memory exhaustion, potentially resulting in an Out-Of-Memory (OOM) kill and Denial of Service (DoS) for the Envoy proxy. This vulnerability is fixed in 1.35.11, 1.36.7, 1.37.3, and 1.38.1.

AnalysisAI

Denial of service in Envoy proxy (versions 1.23.0 through 1.35.10, 1.36.6, 1.37.2, and 1.38.0) allows remote unauthenticated attackers to crash the proxy by sending a specially crafted, highly compressed zstd payload that triggers massive memory allocation in the ZstdDecompressorImpl, leading to Out-Of-Memory kills. The flaw is a decompression-bomb (data amplification) issue that only manifests when zstd decompression is enabled. No public exploit identified at time of analysis, and the issue is not listed in CISA KEV; the high CVSS reflects availability impact only (A:H, no confidentiality or integrity loss).

Technical ContextAI

Envoy is a widely deployed C++ L4/L7 edge and service proxy used as the data plane in service meshes (e.g., Istio) and API gateways. The vulnerability lives in Envoy's zstd decompression filter (ZstdDecompressorImpl), which transparently inflates zstd-compressed request or response bodies. Zstandard supports very high compression ratios, so a small crafted input can expand to gigabytes when decompressed. The root cause maps to CWE-409 (Improper Handling of Highly Compressed Data, i.e., a 'decompression bomb' / data amplification) - the decompressor allocates memory proportional to the declared/produced output without an effective bound, allowing a tiny payload to exhaust process memory.

RemediationAI

Vendor-released patch: upgrade to Envoy 1.35.11, 1.36.7, 1.37.3, or 1.38.1 (whichever matches your release line); for the 1.23.x-1.34.x range, move to a supported fixed line as those branches are not separately patched. Per the advisory at https://github.com/envoyproxy/envoy/security/advisories/GHSA-m3p9-47wh-88wg, this is the primary fix. If immediate patching is not possible, the most direct compensating control is to disable the zstd decompressor filter, which fully removes the attack surface but at the cost of losing transparent zstd decompression for downstream/upstream traffic; alternatively, enforce strict memory limits via Envoy's overload manager and per-connection/per-request buffer limits so an OOM degrades gracefully rather than killing the process, and restrict which clients can send compressed bodies (e.g., terminate untrusted compression at an upstream WAF). Note that overload-manager and buffer-limit mitigations reduce blast radius but do not eliminate the amplification, so patching remains required.