Cyber Resilience

CVE-2025-27149

Zulip Server 2.1.0 – 10.0

Published
31 March 2025
Modified
27 September 2025
CVSS Score v4 4.6
Click a component to see what it means
Raw vectorCVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:A/VC:L/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
EPSS Score 0.0028 21th percentile
Risk Priority 35 floored blend · peak EPSS

Summary

CVE-2025-27149 is a medium-severity Exposure of Sensitive System Information to an Unauthorized Control Sphere (CWE-497) vulnerability in Zulip Zulip Server. Its CVSS base score is 4.6 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique System Information Discovery (T1082); ranked at the 21th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to AC-3 (Access Enforcement) and AC-4 (Information Flow Enforcement) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

A01:2025 Broken Access Control

EU & UK References

Vulnerability Data

Zulip server provides an open-source team chat that helps teams stay productive and focused. Prior to 10.0, the data export to organization administrators feature in Zulip leaks private data. The collection of user-agent types identifying specific integrations or HTTP libraries…

more

(E.g., ZulipGitlabWebhook, okhttp, or PycURL) that have been used to access any organization on the server was incorrectly included in all three export types, regardless of if they were used to access the exported organization or not. The "public data" and "with consent" exports metadata including the titles of some topics in private channels which the administrator otherwise did not have access to, and none of the users consented to exporting and metadata for which users were in a group DM together. This vulnerability is fixed in 10.0.

CWE(s)
CWE-497

Related Threats

MITRE ATT&CK Enterprise Techniques

T1082 System Information Discovery Discovery
An adversary may attempt to get detailed information about the operating system and hardware, including version, patches, hotfixes, service packs, and architecture.
attack.mitre.org →
T1614 System Location Discovery Discovery
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2023-47642Same product: Zulip Zulip Server
CVE-2024-27286Same product: Zulip Zulip Server
CVE-2024-56136Same product: Zulip Zulip Server
CVE-2026-24050Same product: Zulip Zulip Server
CVE-2024-21630Same product: Zulip Zulip Server
CVE-2025-30369Same product: Zulip Zulip Server
CVE-2026-40300Same product: Zulip Zulip Server
CVE-2023-33186Same product: Zulip Zulip Server
CVE-2025-31478Same product: Zulip Zulip Server
CVE-2024-36612Same product: Zulip Zulip Server

Affected Assets

zulip
zulip server
2.1.0 — 10.0

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 · 4 OS baselines
Validate
Prove the fix (OWASP ASVS)
  • V14.1.2

Mitigating Controls (NIST 800-53 r5) AI

AC-3 Access Enforcement good match

Enforces approved authorizations for logical access, directly stopping unauthorized actors from reaching sensitive system information.

AC-4 Information Flow Enforcement good match

Enforces information flow policies that block sensitive system data from crossing into unauthorized control spheres.

AC-6 Least Privilege good match

Limits privileges so that only the minimum necessary access is granted, reducing the chance of exposing system-level details.

SC-7 Boundary Protection partial match

Controls communications at external and key internal boundaries to keep sensitive system information inside authorized spheres.

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 mostly match
prevents

Enforcing least-privilege access permissions directly prevents unauthorized actors from reaching sensitive system information.

PR.IR-01 mostly match
prevents

Protecting environments from unauthorized logical access stops exposure of internal system details to outsiders.

PR.PS-06 partial match
prevents

Secure-development practices reduce the chance of code paths that leak sensitive system information.

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.

A.7.3 Securing offices, rooms and facilities none match
none

Keeping internal maps, directories, and signage from public view prevents disclosure of system or facility details that could aid reconnaissance or targeted attacks.

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-248551 A sticky bit must be set on all OL 8 public directories to prevent unauthorized and unintended information transferred via shared system resources. prevents CWE-497
  • V-248580 OL 8 must prevent kernel profiling by unprivileged users. prevents CWE-497
RHEL 8 (1 rule)
  • V-230270 RHEL 8 must prevent kernel profiling by unprivileged users. prevents CWE-497
Ubuntu 22.04 (1 rule)
  • V-260470 Ubuntu 22.04 LTS, when booted, must require authentication upon booting into single-user and maintenance modes. prevents CWE-497
Ubuntu 24.04 (1 rule)
  • V-270675 Ubuntu 24.04 LTS when booted must require authentication upon booting into single-user and maintenance modes. prevents CWE-497

References