Security readout for executives and security teams
Plain-English summary
A crafted link that appears to target a trusted Jupyter Notebook server can send the browser to another website. This is mainly a phishing and trust-abuse issue, not direct server compromise. Risk is higher where notebook hostnames are known or reachable. The issue is fixed in Jupyter Notebook 6.1.5.
Executive priority
Treat this as a moderate-priority hygiene fix. It can support phishing against trusted analytics environments, but the provided evidence does not indicate active exploitation or direct server takeover. Prioritize internet-facing or widely shared notebook servers first.
Technical view
CVE-2020-26215 is a CWE-601 open redirect in Jupyter Notebook before 6.1.5. The CVSS 3.1 score is 4.4 with network attack vector, high complexity, low privileges, and required user interaction. The advisory says all notebook servers are technically affected, but practical abuse requires a known notebook server host.
Likely exposure
Exposure is likely in environments running Jupyter Notebook versions earlier than 6.1.5, especially research, data science, developer, or education servers with hostnames known to users or attackers. Publicly reachable notebook servers increase phishing usefulness, but the source bundle does not indicate broad unauthenticated server compromise.
Exploitation context
The source bundle does not show active exploitation, and the CVE is not marked KEV. Abuse depends on convincing a user to follow a crafted link tied to a known notebook host. The outcome described is redirection to a spoofed public site, with limited integrity and availability impact.
Researcher notes
The key constraint is host knowledge: all notebook servers are technically affected, but crafted links are only reasonably made for known hosts. Validate version exposure and redirect handling without publishing weaponizable examples. The upstream patch reference is available, but the bundle does not provide separate mitigation details beyond upgrading.
Mitigation direction
- Upgrade Jupyter Notebook to version 6.1.5 or later.
- Apply relevant distribution security updates, including Debian LTS updates where applicable.
- Check current vendor guidance for supported package-specific remediation.
- Reduce unnecessary public exposure of notebook servers.
- Warn users not to trust notebook links solely by hostname appearance.
Validation and detection
- Inventory Jupyter Notebook deployments and record installed versions.
- Confirm no server remains on Jupyter Notebook earlier than 6.1.5.
- Review externally reachable notebook hostnames and access paths.
- Verify relevant Debian systems received the DLA 2477-1 security update.
- Check security awareness materials for guidance on spoofed notebook links.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-601: User-session and phishing behavior lookup
Client-side and session-facing weaknesses should be reviewed alongside initial-access and user-execution behaviors. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2020-26215 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 4.4 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:N/I:L/A:L
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:N/I:L/A:L1.32.7Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
4.4MediumVector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:N/I:L/A:L
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/jupyter/notebook/security/advisories/GHSA-c7vm-f5p4-8fqhCVE reference · x_refsource_CONFIRM
- https://github.com/jupyter/notebook/commit/3cec4bbe21756de9f0c4bccf18cf61d840314d74CVE reference · x_refsource_MISC
- [debian-lts-announce] 20201202 [SECURITY] [DLA 2477-1] jupyter-notebook security updateCVE reference · mailing-list, x_refsource_MLIST
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
URL Redirection to Untrusted Site ('Open Redirect')
URL Redirection to Untrusted Site ('Open Redirect') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.