CVE-2024-39691
Malicious Matrix homeserver can leak truncated message content of messages it shouldn't have access to
matrix-appservice-irc is a Node.js IRC bridge for the Matrix messaging protocol. The fix for GHSA-wm4w-7h2q-3pf7 / CVE-2024-32000 included in matrix-appservice-irc 2.0.0 relied on the Matrix homeserver-provided timestamp to determine whether a user has access to the event they're replying to when determining whether or not to include a truncated version of the original event in the IRC message. Since this value is controlled by external entities, a malicious Matrix homeserver joined to a room in which a matrix-appservice-irc bridge instance (before version 2.0.1) is present can fabricate the timestamp with the intent of tricking the bridge into leaking room messages the homeserver should not have access to. matrix-appservice-irc 2.0.1 drops the reliance on origin_server_ts when determining whether or not an event should be visible to a user, instead tracking the event timestamps internally. As a workaround, it's possible to limit the amount of information leaked by setting a reply template that doesn't contain the original message.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- None
What an attacker can affect
- Confidentiality
- Low
- Integrity
- None
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Malicious Matrix homeserver can leak truncated message content of messages it shouldn't have access to
matrix-appservice-irc is a Node.js IRC bridge for the Matrix messaging protocol. The fix for GHSA-wm4w-7h2q-3pf7 / CVE-2024-32000 included in matrix-appservice-irc 2.0.0 relied on the Matrix homeserver-provided timestamp to determine whether a user has access to the event they're replying to when determining whether or not to include a truncated version of the original event in the IRC message. Since this value is controlled by external entities, a malicious Matrix homeserver joined to a room in which a matrix-appservice-irc bridge instance (before version 2.0.1) is present can fabricate the timestamp with the intent of tricking the bridge into leaking room messages the homeserver should not have access to. matrix-appservice-irc 2.0.1 drops the reliance on origin_server_ts when determining whether or not an event should be visible to a user, instead tracking the event timestamps internally. As a workaround, it's possible to limit the amount of information leaked by setting a reply template that doesn't contain the original message.
- Record
CVE-2024-39691- CVSS 3.1
- 4.3 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N - Weakness
- CWE-280, CWE-755
- Updated
- 2026-11-02
EUVDEUVD-2024-2434
matrix-appservice-irc is a Node.js IRC bridge for the Matrix messaging protocol. The fix for GHSA-wm4w-7h2q-3pf7 / CVE-2024-32000 included in matrix-appservice-irc 2.0.0 relied on the Matrix homeserver-provided timestamp to determine whether a user has access to the event they're replying to when determining whether or not to include a truncated version of the original event in the IRC message. Since this value is controlled by external entities, a malicious Matrix homeserver joined to a room in which a matrix-appservice-irc bridge instance (before version 2.0.1) is present can fabricate the timestamp with the intent of tricking the bridge into leaking room messages the homeserver should not have access to. matrix-appservice-irc 2.0.1 drops the reliance on origin_server_ts when determining whether or not an event should be visible to a user, instead tracking the event timestamps internally. As a workaround, it's possible to limit the amount of information leaked by setting a reply template that doesn't contain the original message.
- Record
EUVD-2024-2434- CVSS 3.1
- 4.3 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-w9mh-5x8j-9754
Malicious Matrix homeserver can leak truncated message content of messages it shouldn't have access to
Impact
The fix for GHSA-wm4w-7h2q-3pf7 / CVE-2024-32000 included in matrix-appservice-irc 2.0.0 relied on the Matrix homeserver-provided timestamp to determine whether a user has access to the event they're replying to when determining whether or not to include a truncated version of the original event in the IRC message. Since this value is controlled by external entities, a malicious Matrix homeserver joined to a room in which a matrix-appservice-irc bridge instance (before version 2.0.1) is present can fabricate the timestamp with the intent of tricking the bridge into leaking room messages the homeserver should not have access to.
Patches
matrix-appservice-irc 2.0.1 drops the reliance on origin_server_ts when determining whether or not an event should be visible to a user, instead tracking the event timestamps internally.
Workarounds
It's possible to limit the amount of information leaked by setting a reply template that doesn't contain the original message. See these lines in the configuration file.
References
For more information
If you have any questions or comments about this advisory, please email us at security at matrix.org.
- Record
GHSA-w9mh-5x8j-9754- CVSS 3.1
- 4.3 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N - Weakness
- CWE-280, CWE-755
- Updated
- 2026-11-02
NVD
matrix-appservice-irc is a Node.js IRC bridge for the Matrix messaging protocol. The fix for GHSA-wm4w-7h2q-3pf7 / CVE-2024-32000 included in matrix-appservice-irc 2.0.0 relied on the Matrix homeserver-provided timestamp to determine whether a user has access to the event they're replying to when determining whether or not to include a truncated version of the original event in the IRC message. Since this value is controlled by external entities, a malicious Matrix homeserver joined to a room in which a matrix-appservice-irc bridge instance (before version 2.0.1) is present can fabricate the timestamp with the intent of tricking the bridge into leaking room messages the homeserver should not have access to. matrix-appservice-irc 2.0.1 drops the reliance on origin_server_ts when determining whether or not an event should be visible to a user, instead tracking the event timestamps internally. As a workaround, it's possible to limit the amount of information leaked by setting a reply template that doesn't contain the original message.
- Record
CVE-2024-39691- CVSS 3.1
- 4.3 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N - Weakness
- CWE-280, CWE-755
- Updated
- 2026-11-02
OSV
Malicious Matrix homeserver can leak truncated message content of messages it shouldn't have access to
matrix-appservice-irc is a Node.js IRC bridge for the Matrix messaging protocol. The fix for GHSA-wm4w-7h2q-3pf7 / CVE-2024-32000 included in matrix-appservice-irc 2.0.0 relied on the Matrix homeserver-provided timestamp to determine whether a user has access to the event they're replying to when determining whether or not to include a truncated version of the original event in the IRC message. Since this value is controlled by external entities, a malicious Matrix homeserver joined to a room in which a matrix-appservice-irc bridge instance (before version 2.0.1) is present can fabricate the timestamp with the intent of tricking the bridge into leaking room messages the homeserver should not have access to. matrix-appservice-irc 2.0.1 drops the reliance on origin_server_ts when determining whether or not an event should be visible to a user, instead tracking the event timestamps internally. As a workaround, it's possible to limit the amount of information leaked by setting a reply template that doesn't contain the original message.
- Record
CVE-2024-39691- CVSS 3.1
- 4.3 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N - Weakness
- CWE-280, CWE-755
- Updated
- 2026-11-02
OSVGHSA-w9mh-5x8j-9754
Malicious Matrix homeserver can leak truncated message content of messages it shouldn't have access to
Impact
The fix for GHSA-wm4w-7h2q-3pf7 / CVE-2024-32000 included in matrix-appservice-irc 2.0.0 relied on the Matrix homeserver-provided timestamp to determine whether a user has access to the event they're replying to when determining whether or not to include a truncated version of the original event in the IRC message. Since this value is controlled by external entities, a malicious Matrix homeserver joined to a room in which a matrix-appservice-irc bridge instance (before version 2.0.1) is present can fabricate the timestamp with the intent of tricking the bridge into leaking room messages the homeserver should not have access to.
Patches
matrix-appservice-irc 2.0.1 drops the reliance on origin_server_ts when determining whether or not an event should be visible to a user, instead tracking the event timestamps internally.
Workarounds
It's possible to limit the amount of information leaked by setting a reply template that doesn't contain the original message. See these lines in the configuration file.
References
For more information
If you have any questions or comments about this advisory, please email us at security at matrix.org.
- Record
GHSA-w9mh-5x8j-9754- CVSS 3.1
- 4.3 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N - Weakness
- CWE-280, CWE-755
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
matrix-appservice-ircnpm |
through 2.0.0 | 2.0.1 |
matrix-appservice-ircnpm |
before 2.0.1 | 2.0.1 |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases, published | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2024-39691 is a medium vulnerability (CVSS 4.3) in Matrix-org Matrix-appservice-irc, published July 5, 2024. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.50%, the 42nd percentile. Fixed in matrix-appservice-irc 2.0.1.
References
github.com/matrix-org/matrix-appservice-irc/security/advisories/GHSA-w9mh-5x8j-9754
nvd.nist.gov/vuln/detail/CVE-2024-39691