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GHSA-w9fg-xffh-p362

MediumCVSS 5.3 / 10
Published Apr 13, 2021·Last modified Mar 13, 2026
Affected Components(0)

No affected components available

Description

Impact

Missing input validation of some parameters on the endpoints used to confirm third-party identifiers could cause excessive use of disk space and memory leading to resource exhaustion.

Patches

The issue is fixed by #9321.

Workarounds

Depending on the needs and configuration of the homeserver a few options are available:

  1. Using email as third-party identifiers be disabled by not configuring the email setting.

  2. Using phone numbers as third-party identifiers can be disabled by ensuring that account_threepid_delegates.msisdn is not configured.

  3. Additionally, the affected endpoint patterns can be blocked at a reverse proxy:

    • ^/_matrix/client/(r0|unstable)/register/email
    • ^/_matrix/client/(r0|unstable)/register/msisdn
    • ^/_matrix/client/(r0|unstable)/account/password
    • ^/_matrix/client/(r0|unstable)/account/3pid
Risk Scores
Base Score
5.3

The vulnerability can be exploited over the network without needing physical access. It is difficult for an attacker to exploit this vulnerability and may require special conditions. An attacker needs basic access or low-level privileges. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a high impact on the availability of the system.

Threat Intelligence
4.9

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
1.54%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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