# CVE-2026-100677: stoatchat account enumeration in login endpoint

Source: https://junglewise.ai/threats/cve-2026-100677-stoatchat-before-0-15-5-contains-an-account-enumeration  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-26. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-100677 · Severity: medium · CVSS 5.3 · Published 2026-09-26

stoatchat is a chat application that secures user accounts through login credentials. An unauthenticated attacker can exploit error messages returned by the login endpoint to enumerate which email addresses are registered, defeating the application's account protection. While the attacker cannot access actual accounts or data, this information can be used to build lists of valid targets for subsequent attacks such as phishing or password spraying.

Technologies: [Stoatchat](https://junglewise.ai/threats/technologies/stoatchat). Vendors: [Stoatchat](https://junglewise.ai/threats/vendors/stoatchat).

## Quick answers

**Is CVE-2026-100677 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-100677 being exploited in the wild.

**How severe is CVE-2026-100677?** Medium severity, with a CVSS score of 5.3, published 26 September 2026.

**Which products and versions are affected?** Stoatchat before 0.15.5.

**Is there a fix for CVE-2026-100677?** A patch was published on 2026-09-26: version 0.15.5 released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-100677 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-100677?** Check whether you run Stoatchat at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability stems from error responses that include source file location fields (file path, line number, column) that differ between code paths for registered versus unregistered accounts. Specifically, POST /api/auth/session/login returns 401 InvalidCredentials with different location fields depending on whether an account exists, allowing unauthenticated network attackers to distinguish between the two cases. The fix was to either normalize error locations or remove location information from client-facing responses, which is implemented in version 0.15.5.

## Affected products

- stoatchat stoatchat before 0.15.5

## Timeline

- 2026-09-26: disclosed
- 2026-09-26: patched: version 0.15.5 released

## References

- [https://github.com/stoatchat/stoatchat/security/advisories/GHSA-h44h-xx2j-hp56](https://github.com/stoatchat/stoatchat/security/advisories/GHSA-h44h-xx2j-hp56)
- [https://www.vulncheck.com/advisories/stoatchat-before-0.15.5-account-enumeration-via-error-location](https://www.vulncheck.com/advisories/stoatchat-before-0.15.5-account-enumeration-via-error-location)

## Related threats

- [stoatchat MFA brute force via insufficient rate limiting](https://junglewise.ai/threats/cve-2026-100678-stoatchat-before-0-15-5-fails-to-enforce-account-level-attempt)
- [stoatchat January media proxy SSRF via SVG image href](https://junglewise.ai/threats/cve-2026-100676-january-the-media-proxy-embed-service-of-stoatchat-stoatchat)
- [stoatchat username validation bypass via Unicode sanitization](https://junglewise.ai/threats/cve-2026-100674-stoatchat-before-0-15-5-fails-to-revalidate-usernames-after)
- [stoatchat SSRF via DNS blocklist bypass in January proxy](https://junglewise.ai/threats/cve-2026-63088-stoatchat-ssrf-via-dns-blocklist-bypass-in-january-proxy)
- [stoatchat delta authorization bypass in webhook fetch endpoint](https://junglewise.ai/threats/cve-2025-71388-stoatchat-delta-authorization-bypass-in-webhook-fetch-endpoint)