CVE-2026-77938

Exploitation

Public exploit code exists. CISA's assessment records a public proof of concept. That is not a report of exploitation in the wild.

SSVC decision

• ExploitationpocPublic proof-of-concept exploit code exists. Not a report of exploitation in the wild.
• AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
• Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.

CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.

EPSS probability

0.41% probability of exploitation activity in the next 30 days.

EPSS percentile

Equal to or higher than the score of 35.6% of scored records. A rank, not a probability.

NVD base score

7.1 (CVSS v4.0), scored by the NVD independently of the CNA.

NVD CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

NVD analysis status

Deferred. NVD last modified this record on 2026-10-20.

Red Hat severity

No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

Published

2026-10-20 00:46Z9 DAYS AGO

Last updated

2026-10-20 13:47Z9 DAYS AGO

Reserved

2026-08-21

Assigning CNA

VulnCheck

Record state

PUBLISHED

Severity

High (CVSS 7.1)

CNA CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

Weaknesses

• CWE-526Cleartext Storage of Sensitive Information in an Environment VariableVariant

Data version

5.2

Document digest

749b5b0f64b01d6258a18ac11415ff6e582fe810de0b498d80e1e7a7e438022e

• www.lasso.securityLasso.security Advisoryhttps://www.lasso.security/vulnerability-database/cve-2026-77938technical-descriptionexploit
• github.comhttps://github.com/letta-ai/letta/blob/1131535716e8a31c9a437f8695e25ac98f203a24/letta/services/tool_sandbox/base.py#L487technical-description
• www.vulncheck.comVulnCheck Advisory: Letta through 0.16.8 Credential Exposure via Tool Sandbox Environment Inheritancehttps://www.vulncheck.com/advisories/letta-through-0.16.8-credential-exposure-via-tool-sandbox-environment-inheritancethird-party-advisory