CVE-2026-77937
highLetta through 0.16.8 contains an authentication bypass vulnerability that allows API callers to impersonate other users by supplying a self-asserted user_id HT…
Letta through 0.16.8 contains an authentication bypass vulnerability that allows API callers to impersonate other users by supplying a self-asserted user_id HTTP header. Attackers can set user_id to another tenant's ID, even with LETTA_SERVER_SECURE enabled, to read and modify that user's agents, memory and configuration.
CVSS
8.1
8.1 (CVSS v3.1)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N Severity source: NVD CVSS v3.1 (disclosure@vulncheck.com)
Timeline (UTC)
Published: 2026-10-20 01:17
Modified: 2026-10-20 20:11
NVD status: Deferred
Last synced 1 day ago
Verified against the source API 2026-10-27 07:04 UTC
Exploitation
Not listed in CISA KEV (as of last catalog sync)
Absence from KEV does not mean a CVE is not exploited. Exploitation status: unknown (no authoritative evidence in our sources).
Affected products
Not reported by the source (unknown — not "none").
Weakness classification (CWE)
Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.
Mitigation & advisories
No vendor advisory or patch reference tagged by NVD. Check the references below.
References
- https://github.com/letta-ai/letta/blob/1131535716e8a31c9a437f8695e25ac98f203a24/letta/serv... disclosure@vulncheck.com
- https://www.lasso.security/vulnerability-database/cve-2026-77937 disclosure@vulncheck.com
- https://www.vulncheck.com/advisories/letta-through-0.16.8-cross-tenant-impersonation-via-u... disclosure@vulncheck.com
Data sources
NVD CVE API 2.0 — fetched 2026-10-27 07:04 UTC · record ↗