Platform
nodejs
Component
pi-mono
Fixed in
0.58.1
0.58.2
0.58.3
0.58.4
0.58.5
CVE-2026-5557 describes an Authentication Bypass vulnerability affecting pi-mono versions 0.58.0 through 0.58.4. This flaw allows attackers to bypass authentication mechanisms within the pi-mom Slack Bot component, specifically through manipulation of the packages/mom/src/slack.ts file. The vulnerability can be exploited remotely, and a public proof-of-concept is now available, increasing the risk of immediate exploitation. A fix is pending.
The core impact of CVE-2026-5557 lies in the ability to bypass authentication within the pi-mono Slack Bot. An attacker exploiting this vulnerability could gain unauthorized access to sensitive information or perform actions on behalf of the bot without proper credentials. This could include accessing Slack channels, sending messages, or potentially integrating with other systems the bot interacts with. Given the public availability of a proof-of-concept, the risk of exploitation is elevated, potentially leading to data breaches, unauthorized system access, and reputational damage. The attack vector is remote, meaning an attacker doesn't need local access to the system running pi-mono.
CVE-2026-5557 is currently considered a high-risk vulnerability due to the public availability of a proof-of-concept. While no active exploitation campaigns have been publicly confirmed, the ease of exploitation significantly increases the likelihood of attacks. The vulnerability was disclosed on 2026-04-05, and the vendor was contacted but did not respond. This lack of vendor engagement further elevates the risk.
Exploit Status
EPSS
0.06% (18% percentile)
CISA SSVC
CVSS Vector
The primary mitigation for CVE-2026-5557 is to upgrade to a patched version of pi-mono as soon as it becomes available. Until a patch is released, restrict access to the vulnerable endpoint (packages/mom/src/slack.ts) using network firewalls or access control lists. Implement strict input validation on any data processed by the Slack bot to prevent malicious manipulation. Consider temporarily disabling the Slack bot integration if upgrading or implementing access controls is not immediately feasible. Monitor Slack channel activity for suspicious behavior. After applying any mitigation, verify its effectiveness by attempting to trigger the authentication bypass manually.
Update the pi-mono package to a patched version. The CVE description indicates the vulnerability exists in versions 0.58.0 to 0.58.4, so updating to the latest available version is recommended to mitigate the risk of authentication bypass.
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CVE-2026-5557 is a vulnerability in pi-mono versions 0.58.0–0.58.4 that allows attackers to bypass authentication by manipulating the Slack bot's channel processing.
You are affected if you are using pi-mono versions 0.58.0 through 0.58.4 and have not yet upgraded to a patched version.
Upgrade to a patched version of pi-mono as soon as it becomes available. Until then, restrict access to the vulnerable endpoint and implement strict input validation.
While no active exploitation campaigns have been publicly confirmed, a public proof-of-concept exists, increasing the risk of exploitation.
Due to lack of vendor response, an official advisory is not currently available. Monitor the pi-mono project's repository and community channels for updates.
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