CVE-2023-35945

Envoy vulnerable to HTTP/2 memory leak in nghttp2 codec

HIGH
7.5
CVSS Score
Published: July 13, 2023 at 08:41 PM UTC
Updated: October 15, 2026 at 12:16 AM UTC
2 products affected across 2 vendorsEnvoyNGHTTP2

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Severity
HIGH7.5
Exploit prediction
EPSS 2%
SSVC
PoC

Description

Envoy is a cloud-native high-performance edge/middle/service proxy. Envoy’s HTTP/2 codec may leak a header map and bookkeeping structures upon receiving `RST_STREAM` immediately followed by the `GOAWAY` frames from an upstream server. In nghttp2, cleanup of pending requests due to receipt of the `GOAWAY` frame skips de-allocation of the bookkeeping structure and pending compressed header. The error return [code path] is taken if connection is already marked for not sending more requests due to `GOAWAY` frame. The clean-up code is right after the return statement, causing memory leak. Denial of service through memory exhaustion. This vulnerability was patched in versions(s) 1.26.3, 1.25.8, 1.24.9, 1.23.11.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 1.23.111.24.0 ≤ v < 1.24.91.25.0 ≤ v < 1.25.81.26.0 ≤ v < 1.26.3
Affected range stops below 1.23.11, so it looks safe — our inference, not a vendor statement
Affected range stops below 1.24.9, so it looks safe — our inference, not a vendor statement
Affected range stops below 1.25.8, so it looks safe — our inference, not a vendor statement
Affected range stops below 1.26.3, so it looks safe — our inference, not a vendor statement
v < 1.55.1
Affected range stops below 1.55.1, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCPoCAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGHGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-400CWE-459

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