Security readout for executives and security teams
Plain-English summary
GitLab had an authorization flaw that could let a highly privileged user misuse Slack or Mattermost integrations so slash commands run as another user. The issue affects older GitLab CE/EE versions and can impact confidentiality and integrity, but the CVE does not indicate confirmed active exploitation.
Executive priority
Prioritize remediation for internet-facing or business-critical GitLab instances using chat integrations. The issue can affect sensitive data and actions, but prerequisites reduce emergency likelihood compared with unauthenticated flaws.
Technical view
CVE-2023-5356 is CWE-863 incorrect authorization in GitLab CE/EE. Affected ranges are versions from 8.13 before 16.5.6, 16.6 before 16.6.4, and 16.7 before 16.7.2. The vector is network reachable, high complexity, high privileges required, user interaction required, with changed scope and high confidentiality and integrity impact.
Likely exposure
Exposure is mainly self-managed GitLab CE/EE instances running affected versions with Slack or Mattermost integrations configured. Organizations without those integrations or already on fixed versions are less likely to be exposed based on the CVE description.
Exploitation context
The CVE has a high CVSS score of 7.3, but exploitation requires high privileges and user interaction. KEV is false in the provided bundle, so there is no cited evidence here of active exploitation.
Researcher notes
Public technical detail may be incomplete because the GitLab issue and HackerOne report are marked permissions-required in the bundle. Do not assume broader impact beyond Slack or Mattermost integration abuse described in the CVE.
Mitigation direction
- Upgrade GitLab to 16.5.6, 16.6.4, 16.7.2, or a later supported version.
- Review GitLab vendor guidance for any additional product-specific mitigation.
- Temporarily restrict or disable Slack and Mattermost integrations until upgraded.
- Review integration permissions and remove unnecessary privileged access.
Validation and detection
- Inventory all GitLab CE/EE versions and compare them with the affected ranges.
- Identify projects or groups using Slack or Mattermost integrations.
- Review GitLab and chat integration logs for unexpected slash-command activity.
- Confirm upgraded instances report a fixed or later GitLab version.
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-863: Authorization and privilege behavior lookup
Authorization weaknesses can support privilege escalation and valid-account review, depending on exploit path. 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-2023-5356 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
- High
- CVSS
- 7.3 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:C/C:H/I:H/A:N
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:H/UI:R/S:C/C:H/I:H/A:N15.8Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.3HighVector: CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:C/C:H/I:H/A:N
Source materials
- CVE List V5 sourceCVE List V5
- GitLab Issue #427154CVE reference · issue-tracking, permissions-required
- HackerOne Bug Bounty Report #2188868CVE reference · technical-description, exploit
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.
Incorrect Authorization
Incorrect Authorization represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.