7.5

CVE-2021-43826: envoyproxy envoy Use After Free

CVSS: 7.5v3.1HighModified
Published 22-02-2022Last modified 23-04-2025
Open JSON

Vulnerability summary

CVE-2021-43826 is a high (CVSS 7.5) Use After Free vulnerability in envoyproxy envoy. EPSS estimates a 1.06% chance of exploitation in the next 30 days, higher than 64% of scored vulnerabilities.

Overall risk
30/100
0100
Medium · default modelHow is this calculated?
CVSS score
7.5/10
010
High · v3.1 (CVE.org)
EPSS score
1.06%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 2
RHSA-2022:1275RHSA-2022:1276

Timeline

  1. 22-02-2022
    PublishedVulnerability first disclosed.
  2. 23-04-2025
    Last modifiedVulnerability information updated.

Description

Envoy is an open source edge and service proxy, designed for cloud-native applications. In affected versions of Envoy a crash occurs when configured for :ref:`upstream tunneling <envoy_v3_api_field_extensions.filters.network.tcp_proxy.v3.TcpProxy.tunneling_config>` and the downstream connection disconnects while the the upstream connection or http/2 stream is still being established. There are no workarounds for this issue. Users are advised to upgrade.

CVSS metrics

3 scores · 2 sources · 2 versions

EPSS trend

Probability

1.06%

Chance of exploitation in the next 30 days

Percentile

64%

Versus all other CVEs

30-day change

0.00 pp

From 1.06% on 19-09-2026

19-09-202619-10-2026
EPSS score
1.06%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Envoyproxy1 product
  • envoy< 1.18.6 | ≥ 1.19.0, < 1.19.3 | ≥ 1.20.0, < 1.20.2 | ≥ 1.21.0, < 1.21.1

1 vendor · 1 product

References

2 links