CVE-2020-26262Public exploitNetwork attack vector

Loopback service access via peer-address validation bypass

Published Jan 13, 2021 · Updated Aug 4, 2024

Access-control bypass in coturn before 4.5.2 allows remote attackers to relay packets to loopback services via crafted peer addresses. good_peer_addr accepts all-zero peer addresses, while ioa_addr_is_loopback inspects the eighth rather than sixteenth IPv6 byte, so prohibited destinations pass validation. The default loopback restriction is exposed unless explicit peer-deny rules block 0.0.0.0/8, ::1, and ::, allowing access to services bound only to loopback.

CVSS severity7.2
High
EPSS probability1.32%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Access-control bypass in coturn before 4.5.2 allows remote attackers to relay packets to loopback services via crafted peer addresses. good_peer_addr accepts all-zero peer addresses, while ioa_addr_is_loopback inspects the eighth rather than sixteenth IPv6 byte, so prohibited destinations pass validation. The default loopback restriction is exposed unless explicit peer-deny rules block 0.0.0.0/8, ::1, and ::, allowing access to services bound only to loopback.

The record

CVE
CVE-2020-26262
Published
Jan 13, 2021
Updated
Aug 4, 2024
Vendor
coturn
Product
coturn
Classifications
CWE-441, CWE-682, T1090
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 13, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 4.5.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

coturn · coturnversion=< 4.5.2

Published CVSS scores

6.4NISTAV:N/AC:L/Au:N/C:P/I:P/A:N
7.2GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-441Unintended Proxy or Intermediary ('Confused Deputy')
CWE-682Incorrect Calculation
T1090Proxy

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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