CVE-2022-39250
Prior to version 19.7.0, an attacker cooperating with a malicious homeserver could interfere with the verification flow between two users, injecting its own cross-signing user identity in place of one of the users’ identities.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (1.00%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
Matrix JavaScript SDK is the Matrix Client-Server software development kit (SDK) for JavaScript. Prior to version 19.7.0, an attacker cooperating with a malicious homeserver could interfere with the verification flow between two users, injecting its own cross-signing user identity in place of one of the users’ identities. This would lead to the other device trusting/verifying the user identity under the control of the homeserver instead of the intended one. The vulnerability is a bug in the matrix-js-sdk, caused by checking and signing user identities and devices in two separate steps, and inadequately fixing the keys to be signed between those steps. Even though the attack is partly made possible due to the design decision of treating cross-signing user identities as Matrix devices on the server side (with their device ID set to the public part of the user identity key), no other examined implementations were vulnerable. Starting with version 19.7.0, the matrix-js-sdk has been modified to double check that the key signed is the one that was verified instead of just referencing the key by ID. An additional check has been made to report an error when one of the device ID matches a cross-signing key. As this attack requires coordination between a malicious homeserver and an attacker, those who trust their homeservers do not need a particular workaround.
- CVSS 3.1
- 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
- EPSS
- 1.00% probability · 61th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-287, CWE-322
- Affected
- matrix/javascript sdk
- Source
- security-advisories@github.com
References
- https://github.com/matrix-org/matrix-js-sdk/commit/a587d7c36026fe1fcf93dfff63588abee359be76Patch, Third Party Advisory
- https://github.com/matrix-org/matrix-js-sdk/releases/tag/v19.7.0Release Notes, Third Party Advisory
- https://github.com/matrix-org/matrix-js-sdk/security/advisories/GHSA-5w8r-8pgj-5jmfThird Party Advisory
- https://matrix.org/blog/2022/09/28/upgrade-now-to-address-encryption-vulns-in-matrix-sdks-and-clientsVendor Advisory
- https://security.gentoo.org/glsa/202210-35Third Party Advisory
- https://github.com/matrix-org/matrix-js-sdk/commit/a587d7c36026fe1fcf93dfff63588abee359be76Patch, Third Party Advisory
- https://github.com/matrix-org/matrix-js-sdk/releases/tag/v19.7.0Release Notes, Third Party Advisory
- https://github.com/matrix-org/matrix-js-sdk/security/advisories/GHSA-5w8r-8pgj-5jmfThird Party Advisory
- https://matrix.org/blog/2022/09/28/upgrade-now-to-address-encryption-vulns-in-matrix-sdks-and-clientsVendor Advisory
- https://security.gentoo.org/glsa/202210-35Third Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.