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No exploitation reportedFix available

CVE-2020-26262

No exploitation reported by the sources we read.

  • Published2021-01-13
  • WeaknessCWE-441 · CWE-682

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

Coturn is free open source implementation of TURN and STUN Server. Coturn before version 4.5.2 by default does not allow peers to connect and relay packets to loopback addresses in the range of `127.x.x.x`. However, it was observed that when sending a `CONNECT` request with the `XOR-PEER-ADDRESS` value of `0.0.0.0`, a successful response was received and subsequently, `CONNECTIONBIND` also received a successful response. Coturn then is able to relay packets to the loopback interface. Additionally, when coturn is listening on IPv6, which is default, the loopback interface can also be reached by making use of either `[::1]` or `[::]` as the peer address. By using the address `0.0.0.0` as the peer address, a malicious user will be able to relay packets to the loopback interface, unless `--denied-peer-ip=0.0.0.0` (or similar) has been specified. Since the default configuration implies that loopback peers are not allowed, coturn administrators may choose to not set the `denied-peer-ip` setting. The issue patched in version 4.5.2. As a workaround the addresses in the address block `0.0.0.0/8`, `[::1]` and `[::]` should be denied by default unless `--allow-loopback-peers` has been specified.

Timeline

dates in UTC
  1. 2021-01-1319:15CVE publishedNVD

Versions per branch

NVD
Fedoraproject fedora
BranchAffectedFixed in
32.x= 32no fix published
33.x= 33no fix published
Coturn project coturn
BranchAffectedFixed in
4.5< 4.5.24.5.2

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • coturnUbuntu:20.04:LTSall versions · fixed in 4.5.1.1-1.1ubuntu0.20.04.2
  • coturnUbuntu:18.04:LTSall versions · fixed in 4.5.0.7-1ubuntu2.18.04.3
  • coturnUbuntu:16.04:LTSall versions · fixed in 4.5.0.3-1ubuntu0.4
  • coturnopenSUSE:Tumbleweedall versions · fixed in 4.5.2-2.2
  • coturnMageia:7all versions · fixed in 4.5.2-1.4.mga7
  • coturnDebian:14all versions · fixed in 4.5.2-1
  • coturnDebian:13all versions · fixed in 4.5.2-1
  • coturnDebian:12all versions · fixed in 4.5.2-1

15 more package ranges on OSV.dev

Vendor advisories

  • CVE-2020-26262 Red Hat Product Security

    coturn: Loopback access control bypass

Full record on NVD

Fix

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

  • CNACVSS 3.17.2known since 2026-10-23
  • NVDCVSS 3.17.2read 2026-10-23
  • NVDCVSS 2.06.4read 2026-10-23
  • CNAweakness (CWE)CWE-441, CWE-682known since 2026-10-23
  • FIRST EPSSEPSS score1.5 %2026-11-09
  • OSVaffected packages—

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
Published
2021-01-13
Last Modified
2026-06-17
NVD status
Modified

Frequently asked questions

What is CVE-2020-26262?

Coturn is free open source implementation of TURN and STUN Server. Coturn before version 4.5.2 by default does not allow peers to connect and relay packets to loopback addresses in the range of `127.x.x.x`. However, it was observed that when sending a `CONNECT` request with the `XOR-PEER-ADDRESS` value of `0.0.0.0`, a successful response was received and subsequently, `CONNECTIONBIND` also received a successful response. Coturn then is able to relay packets to the loopback interface. Additionally, when coturn is listening on IPv6, which is default, the loopback interface can also be reached by making use of either `[::1]` or `[::]` as the peer address. By using the address `0.0.0.0` as the peer address, a malicious user will be able to relay packets to the loopback interface, unless `--denied-peer-ip=0.0.0.0` (or similar) has been specified. Since the default configuration implies that loopback peers are not allowed, coturn administrators may choose to not set the `denied-peer-ip` setting. The issue patched in version 4.5.2. As a workaround the addresses in the address block `0.0.0.0/8`, `[::1]` and `[::]` should be denied by default unless `--allow-loopback-peers` has been specified.

Is CVE-2020-26262 actively exploited?

Active exploitation of CVE-2020-26262 has not been confirmed. Its EPSS score was 1.5% on 2026-11-09, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2020-26262?

CVE-2020-26262 has a CVSS v3 base score of 7.2 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N.

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