MediumCVE-2026-66885

Livebook Teams identity callback lacks state binding, allowing login CSRF (CVE-2026-66885)

Published 05.08.2026Last modified 24.10.2026Sources: CVE.org, OSV

What is affected, what to do

Update Livebook to version 0.18.7, Livebook to version 0.19.9, Livebook to version 0.18.7-cuda12.

Affected: Livebook lt 0.15.0..0.18.7
Livebook lt 0.19.0..0.19.9
Livebook lt 0.15.0-cuda12..0.18.7-cuda12
Livebook lt 0.19.0-cuda12..0.19.9-cuda12
Fixed in: Livebook 0.18.7
Livebook 0.19.9
Livebook 0.18.7-cuda12
Livebook 0.19.9-cuda12

Not sure whether and how you are affected? Ask a question about this vulnerability

Metrics

6.8

Priority

XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

Source: NVD, CVSS v4

6.5

CVSS v3

Severity Medium on the scale from 0 to 10.

Source: CVE.org, OSV

0.2 %

EPSS score

Low — model estimates < 1% exploitation likelihood.

Source: FIRST EPSS, percentile 14.5

Show all metrics

Severity: Medium
Priority (0–325) The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first? Read in glossary: 57.71 Methodology
Exploit maturity An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack. Read in glossary: no public PoC known
XIEM Effective CVSS XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command. Read in glossary: 6.8 Methodology
CVSS v3 CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions. Read in glossary: 6.5
CVSS v4 CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions. Read in glossary: 6.8
EPSS score The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“. Read in glossary: 0.2 %; Low — model estimates < 1% exploitation likelihood.
EPSS percentile The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking. Read in glossary: 14.5; Elevated — this CVE ranks above at least 10% of all CVEs scored today.
KEV status The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching. Read in glossary: —
Published: 05.08.2026
CISA assessment (SSVC): Exploitation: none known · not automatable · Technical impact: partial; Source: CISA Vulnrichment, as of 6 August 2026
CWE CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect. Read in glossary: CWE-352

Detection rules

No NEOSEC detection rule is available for this vulnerability yet.

Classification under NIS2 and CRA

Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

NIS2 NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management. Read in glossary: Handle the vulnerability in regular vulnerability handling under Art. 21(2)(e) NIS2.
CRA The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates. Read in glossary: From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001 ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security. Read in glossary: Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

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.

Source: cvelistv5, OSV (Open Source Vulnerabilities), NVD (NIST)

Affected products

The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

Affected products
		Affected versions	Fixed in
livebook-dev	livebook	`0.19.0-cuda12 – < 0.19.9-cuda12` `0.15.0-cuda12 – < 0.18.7-cuda12` `0.19.0 – < 0.19.9` `0.15.0 – < 0.18.7`	`0.19.9-cuda12` `0.18.7-cuda12` `0.19.9` `0.18.7`
livebook	livebook	`0.15.0 – < 0.18.7` `0.19.0 – < 0.19.9`	`0.18.7` `0.19.9`
hex	livebook	`0.17.0` `0.19.1` `0.17.1` `0.15.1` `0.18.3` `0.18.4` `0.18.5` `0.16.1` `0.19.4` `0.15.4` `0.16.2` `0.18.2` `0.19.0` `0.19.6` `0.15.5` `0.15.3` `0.16.3` `0.16.4` `0.17.3` `0.15.2` `0.16.0` `0.18.6` `0.18.0` `0.19.5` `0.18.1` `0.19.3` `0.17.2` `0.19.2` `0.15.0` `0.19.7` `0.19.8`	— — — — — — — — — — — — — — — — — — — — — — — — — — — — — — —

Vendors and products

Weakness classes (CWE)

CWE-352Cross-Site Request Forgery (CSRF)
Compound
The web application does not, or cannot, sufficiently verify whether a request was intentionally provided by the user who sent the request, which could have originated from an unauthorized actor.
Entry at MITRE CWE-352

References & sources

github.comlivebook-dev/livebook/security/advisories/GHSA-pvvw-28fw-c6fgadvisory, Vendor advisory, related, Vendor advisory
cna.erlef.orgcves/CVE-2026-66885.htmlweb, related, Vendor advisory
github.comlivebook-dev/livebook/commit/21c16168263275541a6e076d0c31852c40…fix, Patch, Patch
github.comlivebook-dev/livebook/commit/33a052daa386c4ce08a9c39a07fc90f353…fix, Patch, Patch
github.comlivebook-dev/livebook/commit/6ed2e213e9d5a19a70d7fcad5a8d616622…fix, Patch, Patch
hex.pmpackages/livebookpackage
OSV (Open Source Vulnerabilities)vulnerability/EEF-CVE-2026-66885related, Third-party advisory

Changes to this CVE

Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

10.08.2026Initial analysis by NVDNVD

Newly listed as affected:

Livebook (0.19.0 – before 0.19.9; 0.15.0 – before 0.18.7)

CVSS V3.1: AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

New references:

and 2 more references

Show 8 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
CVSS	added	—	AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
Product configuration	added	—	OR cpe:2.3:a:livebook:livebook::::::::* versions from (including) 0.19.0 up to (excluding) 0.19.9 cpe:2.3:a:livebook:livebook::::::::* versions from (including) 0.15.0 up to (excluding) 0.18.7
Reference type	added	—	EEF: https://cna.erlef.org/cves/CVE-2026-66885.html Types: Vendor Advisory
Reference type	added	—	EEF: https://github.com/livebook-dev/livebook/commit/21c16168263275541a6e076d0c31852c40e09a18 Types: Patch
Reference type	added	—	EEF: https://github.com/livebook-dev/livebook/commit/33a052daa386c4ce08a9c39a07fc90f353ff6a51 Types: Patch
Reference type	added	—	EEF: https://github.com/livebook-dev/livebook/commit/6ed2e213e9d5a19a70d7fcad5a8d616622cd2084 Types: Patch
Reference type	added	—	EEF: https://github.com/livebook-dev/livebook/security/advisories/GHSA-pvvw-28fw-c6fg Types: Vendor Advisory
Reference type	added	—	EEF: https://osv.dev/vulnerability/EEF-CVE-2026-66885 Types: Third Party Advisory

Source identifier: nvd@nist.gov

05.08.2026ReceivedEEF

CVSS V4.0: AV:N/AC:L/AT:N/PR:L/UI:A/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

Weakness type: CWE-352

Description added or changed

New references:

and 2 more references

Show 10 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Affected versions (publisher)	added	—	livebook, livebook, livebook
Description	added	—	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.
CVSS	added	—	AV:N/AC:L/AT:N/PR:L/UI:A/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
Weakness type (CWE)	added	—	CWE-352
Reference	added	—	https://cna.erlef.org/cves/CVE-2026-66885.html
Reference	added	—	https://github.com/livebook-dev/livebook/commit/21c16168263275541a6e076d0c31852c40e09a18
Reference	added	—	https://github.com/livebook-dev/livebook/commit/33a052daa386c4ce08a9c39a07fc90f353ff6a51
Reference	added	—	https://github.com/livebook-dev/livebook/commit/6ed2e213e9d5a19a70d7fcad5a8d616622cd2084
Reference	added	—	https://github.com/livebook-dev/livebook/security/advisories/GHSA-pvvw-28fw-c6fg
Reference	added	—	https://osv.dev/vulnerability/EEF-CVE-2026-66885

Source identifier: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db

2 NVD translations into other languages are hidden.

Embed badge

Show the severity and KEV status of this vulnerability on your site – with a link back here. The image is updated hourly.

<a href="https://intel.neosec.eu/en/cve/CVE-2026-66885"><img src="https://intel.neosec.eu/badge/cve/CVE-2026-66885.svg?lang=en" alt="CVE-2026-66885 – NEOSEC Intel" height="20"></a>