Cyber Resilience

CVE-2023-32677

Access Control in Zulip ≤ 6.2

Published
19 May 2023
Modified
21 November 2024
Patch / advisory
CVSS Score v3.1 3.1
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N
EPSS Score 0.0056 44th percentile
Risk Priority 29 floored blend · peak EPSS

Summary

CVE-2023-32677 is a low-severity Missing Authorization (CWE-862) vulnerability in Zulip Zulip. Its CVSS base score is 3.1 (Low).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 44th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

OWASP Top 10 for Web (2025)

EU & UK References

Vulnerability Data

Zulip is an open-source team collaboration tool with unique topic-based threading. Zulip administrators can configure Zulip to limit who can add users to streams, and separately to limit who can invite users to the organization. In Zulip Server 6.1 and…

more

below, the UI which allows a user to invite a new user also allows them to set the streams that the new user is invited to -- even if the inviting user would not have permissions to add an existing user to streams. While such a configuration is likely rare in practice, the behavior does violate security-related controls. This does not let a user invite new users to streams they cannot see, or would not be able to add users to if they had that general permission. This issue has been addressed in version 6.2. Users are advised to upgrade. Users unable to upgrade may limit sending of invitations down to users who also have the permission to add users to streams.

CWE(s)

Related Threats

MITRE ATT&CK Enterprise Techniques

T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
T1548 Abuse Elevation Control Mechanism Privilege Escalation
Adversaries may circumvent mechanisms designed to control privilege elevation to gain higher-level permissions.
T1556 Modify Authentication Process Defense Impairment
Adversaries may modify authentication mechanisms and processes to access user credentials or enable otherwise unwarranted access to accounts.
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2023-28623Same product: Zulip Zulip
CVE-2024-21630Same vendor: Zulip
CVE-2025-43838Shared CWE-862
CVE-2023-7268Shared CWE-862
CVE-2024-1158Shared CWE-862
CVE-2024-37427Shared CWE-862
CVE-2025-59561Shared CWE-862
CVE-2025-31533Shared CWE-862
CVE-2024-35725Shared CWE-862
CVE-2025-8565Shared CWE-862

Affected Assets

zulip
zulip
≤ 6.2

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

Detect
Catch it (NIST detect / respond)

Harden
Shrink the surface (DISA STIG)
  • 5 hardening rules · 3 OS baselines
Validate
Prove the fix (OWASP ASVS)

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

addresses: CWE-862

Requiring an access control policy ensures authorization checks are defined and applied for critical functions.

addresses: CWE-862

Reviews of access controls detect missing authorization checks on critical functions or resources.

addresses: CWE-862

Documenting permitted unauthenticated actions prevents missing authorization by making all exceptions explicit and subject to organizational review.

addresses: CWE-862

Requiring attribute association with information prevents authorization from being performed without necessary security or privacy context.

addresses: CWE-862

Mandating authorization prior to allowing remote connections addresses missing authorization for remote access.

addresses: CWE-862

Mandating authorization before wireless connections are allowed prevents missing authorization for wireless access.

addresses: CWE-862

The control requires authorization before allowing mobile device connections, directly mitigating missing authorization for system access.

addresses: CWE-862

Requiring approvals for account creation and specifying authorizations ensures authorization is not missing for system access.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.AA-05 full match
prevents

Explicitly requires defining, enforcing, and reviewing authorizations and least privilege, directly preventing missing authorization checks.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

prevents

Requiring authentication and credentials before any access occurs eliminates the absence of authorization checks that would otherwise allow an unauthenticated actor to reach protected resources.

prevents

Requiring formal authorization of every access request before rights are granted ensures that checks for required permissions are performed, preventing missing authorization checks from being introduced.

prevents

Mandatory authorization checks and central records of granted rights ensure that every access attempt is preceded by an explicit decision rather than relying on missing checks.

mitigates

Segregating the approval of access rights from their implementation provides an independent check that reduces the impact of missing authorization checks in the resulting system configuration.

finds

By requiring competent outsiders to verify that every function enforces the need-to-know principle, the control lowers the likelihood that missing authorization checks persist undetected.

prevents

Defining authorization responsibilities and reviewing risk-treatment progress throughout the project lifecycle catches missing authorization checks before the system is deployed.

Hardening callouts derived

Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).

Oracle Linux 8 (2 rules)
  • V-248581 OL 8 must require users to provide a password for privilege escalation. prevents CWE-862
  • V-252656 The OL 8 operating system must not be configured to bypass password requirements for privilege escalation. prevents CWE-862
RHEL 7 (2 rules)
  • V-251704 The Red Hat Enterprise Linux operating system must not be configured to bypass password requirements for privilege escalation. prevents CWE-862
  • V-204429 The Red Hat Enterprise Linux operating system must be configured so that users must provide a password for privilege escalation. prevents CWE-862

References