CVE-2020-26261
user-readable api tokens in systemd units
jupyterhub-systemdspawner enables JupyterHub to spawn single-user notebook servers using systemd. In jupyterhub-systemdspawner before version 0.15 user API tokens issued to single-user servers are specified in the environment of systemd units. These tokens are incorrectly accessible to all users. In particular, the-littlest-jupyterhub is affected, which uses systemdspawner by default. This is patched in jupyterhub-systemdspawner v0.15
Attack profile
How easy it is to exploit
- Attack vector
- Local
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- Required
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
user-readable api tokens in systemd units
jupyterhub-systemdspawner enables JupyterHub to spawn single-user notebook servers using systemd. In jupyterhub-systemdspawner before version 0.15 user API tokens issued to single-user servers are specified in the environment of systemd units. These tokens are incorrectly accessible to all users. In particular, the-littlest-jupyterhub is affected, which uses systemdspawner by default. This is patched in jupyterhub-systemdspawner v0.15
- Record
CVE-2020-26261- CVSS 3.1
- 7.9 High
CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N - Weakness
- CWE-668
- Updated
- 2026-11-02
EUVDEUVD-2020-0093
jupyterhub-systemdspawner enables JupyterHub to spawn single-user notebook servers using systemd. In jupyterhub-systemdspawner before version 0.15 user API tokens issued to single-user servers are specified in the environment of systemd units. These tokens are incorrectly accessible to all users. In particular, the-littlest-jupyterhub is affected, which uses systemdspawner by default. This is patched in jupyterhub-systemdspawner v0.15
- Record
EUVD-2020-0093- CVSS 3.1
- 7.9 High
CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-cg54-gpgr-4rm6
user-readable api tokens in systemd units for JupyterHub
Impact
user API tokens issued to single-user servers are specified in the environment of systemd units, which are accessible to all users.
In particular, the-littlest-jupyterhub is affected, which uses systemdspawner by default.
Patches
Patched in jupyterhub-systemdspawner v0.15
Workarounds
No workaround other than upgrading systemdspawner to 0.15
For more information
If you have any questions or comments about this advisory:
- Open a thread in the Jupyter forum
- Email us at [email protected]
- Record
GHSA-cg54-gpgr-4rm6- CVSS 4.0
- 7.3 High
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N/E:U - CVSS 3.1
- 7.9 High
CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N - Weakness
- CWE-668
- Updated
- 2026-11-02
NVD
jupyterhub-systemdspawner enables JupyterHub to spawn single-user notebook servers using systemd. In jupyterhub-systemdspawner before version 0.15 user API tokens issued to single-user servers are specified in the environment of systemd units. These tokens are incorrectly accessible to all users. In particular, the-littlest-jupyterhub is affected, which uses systemdspawner by default. This is patched in jupyterhub-systemdspawner v0.15
- Record
CVE-2020-26261- CVSS 3.1
- 7.9 High
CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N - CVSS 2.0
- 3.3 Low
AV:L/AC:M/Au:N/C:P/I:P/A:N - Weakness
- CWE-668
- Updated
- 2026-11-02
OSV
jupyterhub-systemdspawner enables JupyterHub to spawn single-user notebook servers using systemd. In jupyterhub-systemdspawner before version 0.15 user API tokens issued to single-user servers are specified in the environment of systemd units. These tokens are incorrectly accessible to all users. In particular, the-littlest-jupyterhub is affected, which uses systemdspawner by default. This is patched in jupyterhub-systemdspawner v0.15
- Record
CVE-2020-26261- CVSS 3.1
- 7.9 High
CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N - Updated
- 2026-11-02
OSVGHSA-cg54-gpgr-4rm6
user-readable api tokens in systemd units for JupyterHub
Impact
user API tokens issued to single-user servers are specified in the environment of systemd units, which are accessible to all users.
In particular, the-littlest-jupyterhub is affected, which uses systemdspawner by default.
Patches
Patched in jupyterhub-systemdspawner v0.15
Workarounds
No workaround other than upgrading systemdspawner to 0.15
For more information
If you have any questions or comments about this advisory:
- Open a thread in the Jupyter forum
- Email us at [email protected]
- Record
GHSA-cg54-gpgr-4rm6- CVSS 4.0
- 7.3 High
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N/E:U - CVSS 3.1
- 7.9 High
CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N - Weakness
- CWE-668
- Updated
- 2026-11-02
OSVPYSEC-2020-52 No score
jupyterhub-systemdspawner enables JupyterHub to spawn single-user notebook servers using systemd. In jupyterhub-systemdspawner before version 0.15 user API tokens issued to single-user servers are specified in the environment of systemd units. These tokens are incorrectly accessible to all users. In particular, the-littlest-jupyterhub is affected, which uses systemdspawner by default. This is patched in jupyterhub-systemdspawner v0.15
- Record
PYSEC-2020-52- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
jupyterhub-systemdspawnerPyPI |
before 0.15.0 | 0.15.0 |
jupyterhub-systemdspawnerPyPI |
before 0.15.0, plus listed versions 0.100.110.120.130.14 Show 10 moreShow less0.90.9.10.9.100.9.110.9.120.9.50.9.60.9.70.9.80.9.9 |
0.15.0 |
jupyterhub-systemdspawnerPyPI |
before 0.15.0, plus listed versions 0.90.9.10.9.50.9.60.9.7 Show 10 moreShow less0.9.80.9.90.9.100.9.110.9.120.100.110.120.130.14 |
0.15.0 |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2020-26261 is a high vulnerability (CVSS 7.9) in Jupyterhub Systemdspawner, published December 9, 2020. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.48%, the 41st percentile. Fixed in jupyterhub-systemdspawner 0.15.0.
References
github.com/jupyterhub/systemdspawner/security/advisories/GHSA-cg54-gpgr-4rm6
pypi.org/project/jupyterhub-systemdspawner
nvd.nist.gov/vuln/detail/CVE-2020-26261