# CVE-2026-66885: Livebook Teams identity callback lacks state binding, allowing login CSRF > Attackers can force victims into sessions bound to attacker identities, exposing victim data and attributing work to the attacker. - **Severity:** Medium 6.8 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N`) - **Exploited in the wild:** Not known - **Login needed:** Any signed-in user - **Attackable:** Over the internet - **Victim action needed:** A user has to click or open something - **Fix available:** Yes - **Published:** 5 Aug 2026 - **Updated:** 6 Aug 2026 - **Also known as:** EEF-CVE-2026-66885, GHSA-pvvw-28fw-c6fg ## What is CVE-2026-66885? CVE-2026-66885 is a medium-severity vulnerability in livebook-dev livebook, published on 5 Aug 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link. ### Official description 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. Weakness: CWE-352 (Cross-Site Request Forgery) ## Which versions are affected by CVE-2026-66885? 1 open source package ship an affected version, including livebook. It affects 1 product. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `livebook` | Hex | From 0.15.0 | 0.18.7, 0.19.9 | Products: Livebook Livebook. ## How do I fix CVE-2026-66885? Upgrade livebook to a fixed version for your release line: 0.18.7 or 0.19.9. ## Is CVE-2026-66885 being exploited? There is no known exploitation of CVE-2026-66885 in the wild and no public exploit code. ## Other vulnerabilities in livebook-dev livebook - [CVE-2026-66298](https://insights.sbomify.com/CVE-2026-66298/): JS-view sandboxed output can synthesize keyboard events to trigger unconfirmed global shortcuts (high 8.6) - [CVE-2023-35174](https://insights.sbomify.com/CVE-2023-35174/): Livebook Desktop's protocol handler can be exploited to execute arbitrary command on Windows (high 8.6) - [CVE-2026-68746](https://insights.sbomify.com/CVE-2026-68746/): Livebook Teams identity check fails open when the deployment group is unresolvable, allowing unauthenticated access (high 7.7) - [CVE-2026-66881](https://insights.sbomify.com/CVE-2026-66881/): Path traversal in imported file_entries name allows arbitrary file write via URL-type entry download (high 7.0) - [CVE-2026-66297](https://insights.sbomify.com/CVE-2026-66297/): Unescaped deployment environment variables in generated setup commands (medium 5.0) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-66885 and fix it if it is affected. What it is: CVE-2026-66885 is a medium-severity vulnerability in livebook-dev livebook, published on 5 Aug 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link. Exploitation: There is no known exploitation of CVE-2026-66885 in the wild and no public exploit code. Affected packages and fixed versions: - livebook (Hex): affected from 0.15.0; fixed in 0.18.7, 0.19.9 Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2026-66885/ (Markdown: https://insights.sbomify.com/CVE-2026-66885/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-66885 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-66885 - OSV: https://osv.dev/vulnerability/CVE-2026-66885 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-66885/ Summaries are generated and may contain mistakes; the official description above is the record.