GraylogApplication

CVE-2021-37760

CRITICAL · 9.8 CVSS v3.1 Published 2021-07-31
Fix available
A fix is available. Upgrade to 4.1.2 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A Session ID leak in the audit log in Graylog before 4.1.2 allows attackers to escalate privileges (to the access level of the leaked session ID).

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Graylog before version 4.1.2 has a vulnerability where session IDs are inadvertently written to the audit log. An attacker with access to the audit log can extract these session IDs and use them to hijack sessions, escalating privileges to match the compromised session's access level.

MitigationUpgrade Graylog to version 4.1.2 or later, which addresses the session ID leakage in the audit log. Additionally, restrict access to audit logs to trusted administrators only as a defense-in-depth measure.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
GraylogApplication
Affected:>= 2.1.1, < 4.1.2

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check installed Graylog version
    Run the command to display the Graylog server version (typically `graylog-ctl version` or check the web interface under System > Nodes).
    Affected if The installed version is greater than or equal to 2.1.1 and less than 4.1.2.
  2. Verify audit logging is enabled
    Access the Graylog configuration file or web interface to confirm whether the audit log feature is turned on.
    Affected if Audit logging is enabled and the Graylog version falls within the affected range.
  3. Locate the audit log files
    Identify where Graylog stores audit logs, typically in the configured log directory.
    Affected if Audit logs exist and contain entries from a Graylog version in the affected range.
  4. Inspect audit log for session data
    Open or search the audit log file and look for entries that may contain session identifiers or tokens.
    Affected if The audit log contains visible session IDs or authentication tokens.

You are affected if your Graylog version is between 2.1.1 and 4.1.2 (exclusive) and audit logging is enabled, with any evidence of session IDs present in the audit logs.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 4.1.2 or later
Fixed in 4.1.2
Interim mitigation

Upgrade Graylog to version 4.1.2 or later, which addresses the session ID leakage in the audit log. Additionally, restrict access to audit logs to trusted administrators only as a defense-in-depth measure.

Recommended fix High confidence

Graylog 4.1.2 or later (e.g., latest stable 4.x or 5.x release)

  1. 1. Back up your Graylog configuration and data before proceeding with the upgrade.
  2. 2. Review the Graylog upgrade documentation for your current version to ensure compatibility.
  3. 3. Stop the Graylog service.
  4. 4. Upgrade Graylog to version 4.1.2 or later (e.g., 4.1.2, 4.2.x, or latest stable release).
  5. 5. Verify the upgrade was successful by checking that the audit log no longer contains session IDs.
  6. 6. Restart the Graylog service.

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Graylog Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,750
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.

Scan for this in your stack

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dbcve dependency scanner

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-37760 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data