CVE-2026-66885 — Livebook Teams identity callback lacks state binding, allowing login CSRF
Cross-Site Request Forgery (CSRF) vulnerability in livebook-dev livebook allows an attacker to authenticate a victim's browser session under the attacker's own Livebook Teams identity. When Livebook is configured to use Livebook Teams for identity, Livebook.ZTA.LivebookTeams.handle_request/4 in lib/livebook/zta/livebook_teams.ex handles the OAuth-style callback carrying a teams_identity marker and a code parameter. The clause exchanges that code for an access token and writes the token into the browser session without verifying any value that ties the callback to the browser session that started the login. No state or nonce is generated when the flow is initiated: Livebook.Teams.Requests.create_auth_request/1 in lib/livebook/teams/requests.ex sends an empty request body, so no per-attempt value is ever registered, and the callback clause has nothing to compare against. An attacker who holds membership in the same Livebook Teams organisation as the target instance can therefore begin the login flow themselves, retain the resulting authorization code without redeeming it, and induce a victim to open a crafted URL carrying that code. The victim's browser completes the exchange and the resulting session is bound to the attacker's identity rather than the victim's. The victim is not required to hold any particular privilege, and no credential belonging to the victim is involved. The vulnerability does not allow the attacker to authenticate as the victim. The consequence is that a user believes they are working in their own authenticated session while they are in fact operating as another identity. Work performed in that session is attributed to the attacker's account, and secrets, uploaded data, or notebook results the victim produces are exposed to the attacker rather than kept in the victim's own account. The authorization code must be redeemed within a short window after the login flow begins, which constrains the timing of the attack but not its feasibility. This issue affects livebook: from 0.15.0 before 0.18.7 and from 0.19.0 before 0.19.9.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- EPSS 0.2% (30-day exploitation probability)+2
- Technical severity (medium)+3
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
CISA SSVC assessment CISA
Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
- Documented patch — github.com (NIST National Vulnerability Database)
- Documented patch — github.com (NIST National Vulnerability Database)
- Documented patch — github.com (NIST National Vulnerability Database)
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Livebook Livebook, Livebook-dev Livebook).
- The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
- Apply the fixed version or the patch documented under Remediation.
- Exploitation requires user interaction: tighten email/web filtering and warn affected users.
- Search available logs for exploit probes matching the vulnerability class (csrf), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Livebook | Livebook | ≥ 0.15.0 and < 0.18.7≥ 0.19.0 and < 0.19.9 | Vulnerable | NIST National Vulnerability Database |
| Livebook-dev | Livebook | ≥ 0.15.0 and < 0.18.7≥ 0.19.0 and < 0.19.9≥ 0.15.0-cuda12 and < 0.18.7-cuda12≥ 0.19.0-cuda12 and < 0.19.9-cuda12≥ 4380a411920531223088267ed1c0ad21f96ef660 | Vulnerable | CVE Program (cve.org) e CISA ADP |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 6.8 | CVSS 4.0 | Medium | — | — | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db via NIST National Vulnerability Database |
| 6.8 | CVSS 4.0 | Medium | — | — | EEF via CVE Program (cve.org) e CISA ADP |
| 6.5 | CVSS 3.1 | Medium | 2.8 | 3.6 | nvd@nist.gov via NIST National Vulnerability Database |
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N (score shown at the top: nvd@nist.gov) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Timeline
What happened to this CVE, newest first.
- 2026
- Affected products added · livebook-dev/livebook
- SSVC assessment updated
- Record published
- Fix documented
- CVSS changed · 6.5
- Source status changed · → Analyzed
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× Official description updated · Oct 15, 2026 – Oct 15, 2026
References
6 on the record
- github.com/livebook-dev/livebook/security/advisories/GHSA-pvvw-28fw-c6fg
- cna.erlef.org/cves/CVE-2026-66885.html
- github.com/livebook-dev/livebook/commit/33a052daa386c4ce08a9c39a07fc90f353ff6a51
- github.com/livebook-dev/livebook/commit/6ed2e213e9d5a19a70d7fcad5a8d616622cd2084
- github.com/livebook-dev/livebook/commit/21c16168263275541a6e076d0c31852c40e09a18
- osv.dev/vulnerability/EEF-CVE-2026-66885
Elsewhere on this site
Related CVEs (same products)
- High CVE-2026-68746 Livebook Teams identity check fails open when the deployment group is unresolvable, allowing unauthenticated access Aug 5, 2026
- High CVE-2026-66298 JS-view sandboxed output can synthesize keyboard events to trigger unconfirmed global shortcuts Aug 5, 2026
- High CVE-2026-66881 Path traversal in imported file_entries name allows arbitrary file write via URL-type entry download Aug 5, 2026
- High CVE-2026-66297 Unescaped deployment environment variables in generated setup commands Aug 5, 2026
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2026-66885 is "Livebook Teams identity callback lacks state binding, allowing login CSRF", rated Medium. It affects Livebook (Livebook); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 6.5 describes technical severity. EPSS 0.24% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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