Parsing issue in matrix-org/node-irc leading to room takeovers
Description
matrix-appservice-irc is an open source Node.js IRC bridge for Matrix. Attackers can specify a specific string of characters, which would confuse the bridge into combining an attacker-owned channel and an existing channel, allowing them to grant themselves permissions in the channel. The vulnerability has been patched in matrix-appservice-irc 0.35.0. As a workaround operators may disable dynamic channel joining via dynamicChannels.enabled to prevent users from joining new channels, which prevents any new channels being bridged outside of what is already bridged, and what is specified in the config.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
A parsing issue in matrix-appservice-irc allows attackers to confuse the bridge into merging channels, granting unauthorized permissions.
Vulnerability
Overview
A parsing vulnerability in matrix-appservice-irc, an IRC bridge for Matrix, allows attackers to craft a specific string of characters that confuses the bridge's channel mapping logic [1][4]. This causes the bridge to incorrectly associate an attacker-controlled channel with an existing legitimate channel, effectively merging them [2].
Attack
Vector
To exploit this vulnerability, an attacker needs to be able to send messages to the bridge (e.g., by joining a Matrix room or sending IRC commands) and must have knowledge of the specific character sequence [4]. No special privileges are required beyond normal user access to interact with the bridge. The attack does not require man-in-the-middle positioning or direct access to the IRC server [1][2].
Impact
If successful, the attacker gains the ability to grant themselves permissions (such as operator status) within the affected channel [1]. This can lead to unauthorized channel control, message interception, or disruption of bridged communications [4].
Mitigation
The vulnerability has been patched in matrix-appservice-irc version 0.35.0 [2]. Operators unable to upgrade immediately can disable dynamic channel joining via the dynamicChannels.enabled configuration option to prevent new channels from being bridged, limiting the attack surface [1][4]. The Matrix.org Foundation has updated its bridges on Libera Chat and OFTC [2].
AI Insight generated on May 21, 2026. Synthesized from this CVE's description and the cited reference URLs; citations are validated against the source bundle.
Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
matrix-appservice-ircnpm | < 0.35.0 | 0.35.0 |
Affected products
2- matrix-org/matrix-appservice-ircv5Range: < 0.35.0
Patches
0No patches discovered yet.
Vulnerability mechanics
AI mechanics synthesis has not run for this CVE yet.
References
5- github.com/advisories/GHSA-xvqg-mv25-rwvwghsaADVISORY
- nvd.nist.gov/vuln/detail/CVE-2022-39203ghsaADVISORY
- github.com/matrix-org/matrix-appservice-irc/security/advisories/GHSA-xvqg-mv25-rwvwghsax_refsource_CONFIRMWEB
- matrix.org/blog/2022/09/13/security-release-of-matrix-appservice-irc-0-35-0-high-severityghsaWEB
- matrix.org/blog/2022/09/13/security-release-of-matrix-appservice-irc-0-35-0-high-severity/mitrex_refsource_MISC
News mentions
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