VulnerabilityPublished 5 Aug 2026

CVE-2026-66885: livebook · Cross-Site Request Forgery (CSRF)

Affects livebookSource CVE Database V5

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Not known to be exploited · CVSS 6.8 Medium : upgrade to 0.19.9 or 0.18.7 when convenient.

Data as of 4 Nov 2026, 10:58 UTC

CVSS 4.0 base score

6.8Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.2% chance of exploitation in 30 days – higher than 14% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 0.19.9, 0.18.7, 0.19.9-cuda12 +1

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

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: Low
User Interaction: Active
Vulnerable system confidentiality: High
Vulnerable system integrity: None
Vulnerable system availability: None
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: Low: The attacker requires privileges that provide basic capabilities that are typically limited to settings and resources owned by a single low-privileged user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.
User Interaction: Active: Successful exploitation of this vulnerability requires a targeted user to perform specific, conscious interactions with the vulnerable system and the attacker’s payload, or the user’s interactions would actively subvert protection mechanisms which would lead to exploitation of the vulnerability.
Vulnerable system confidentiality: High: There is a total loss of confidentiality, resulting in all information within the Vulnerable System being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system availability: None: There is no impact to availability within the Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 5 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 4 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade livebook to 0.19.9 or 0.18.7; livebook to 0.19.9-cuda12, 0.19.9, 0.18.7-cuda12 or 0.18.7.

Affected software

Product	Affected	Fixed in
livebook-devlivebook	Affected >=0.19.0 <0.19.9	Fixed in 0.19.9
livebook-devlivebook	Affected >=0.15.0 <0.18.7	Fixed in 0.18.7
livebook-devlivebook	Affected >=0.19.0-cuda12 <0.19.9-cuda12	Fixed in 0.19.9-cuda12
livebook-devlivebook	Affected >=0.19.0 <0.19.9	Fixed in 0.19.9
livebook-devlivebook	Affected >=0.15.0-cuda12 <0.18.7-cuda12	Fixed in 0.18.7-cuda12
livebook-devlivebook	Affected >=0.15.0 <0.18.7	Fixed in 0.18.7

CPE configurations (1)

cpe:2.3:a:livebook-dev:livebook:*:*:*:*:*:*:*:*

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

If you cannot patch yet, users should be cautious when clicking on unsolicited or suspicious URLs related to Livebook Teams authentication flows.

Description

CVE-2026-66885 is a Cross-Site Request Forgery (CSRF) vulnerability in livebook-dev livebook when configured with Livebook Teams for identity. An attacker in the same Livebook Teams organization can cause a victim's browser session to authenticate as the attacker by tricking the victim into using a crafted URL with an authorization code. This results in the victim unknowingly operating under the attacker's identity, exposing any work or secrets to the attacker. The vulnerability affects livebook versions from 0.15.0 before 0.18.7 and from 0.19.0 before 0.19.9. The CVSS 4.0 score is 6.8 (medium severity).

Impact

An attacker can cause a victim's browser session to authenticate as the attacker rather than the victim, leading to the victim's actions and data being attributed to and accessible by the attacker. This does not allow the attacker to authenticate as the victim, but it compromises session integrity and confidentiality of the victim's work and secrets within the livebook environment.

Summary

The vulnerability arises because the OAuth-style callback handling in livebook-dev livebook does not verify any state or nonce tying the authorization code to the initiating browser session. The login flow does not generate or register any per-attempt value, allowing an attacker who shares the same Livebook Teams organization to initiate a login flow, capture the authorization code, and then trick a victim into redeeming that code. The victim's session is then bound to the attacker's identity, not their own. This leads to the victim unknowingly performing actions and exposing data under the attacker's account. The authorization code must be redeemed shortly after issuance, limiting the attack window but not its feasibility.

CWE-352Cross-Site Request Forgery (opens in a new tab)
Compound weaknessLikelihood of exploit: MediumCWE Top 25 (2025): #3OWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
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.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Implementation
Ensure that the application is free of cross-site scripting issues (CWE-79), because most CSRF defenses can be bypassed using attacker-controlled script.
Architecture and Design
Generate a unique nonce for each form, place the nonce into the form, and verify the nonce upon receipt of the form. Be sure that the nonce is not predictable (CWE-330).
OWASP Cheat Sheets
REST Assessment (opens in a new tab)
REST Security (opens in a new tab)
Cross-Site Request Forgery Prevention (opens in a new tab)
Authorization Testing Automation (opens in a new tab)
Insecure Direct Object Reference Prevention (opens in a new tab)
OWASP ASVS 4.0.3
V13.2.3 (opens in a new tab)
V4.2.2 (opens in a new tab)
V13.3.2 (opens in a new tab)
Attack patterns
JSON Hijacking (aka JavaScript Hijacking) (opens in a new tab)
Cross-Domain Search Timing (opens in a new tab)
Cross Site Identification (opens in a new tab)
Cross Site Request Forgery (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

CPE configurations (1)

Description

AI analysisMachine-generated, updated 13 Aug 2026, 17:32 UTC

WeaknessesCWE-352

Technical details

References

Community reviews

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