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Resource Allocation Without LimitsWeakness · CWE-770

CVE-2025-8396

MEDIUM · 6.9 CVSS v4.0 Published 2025-09-15
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
78/100
Remediation priority · High
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
Insufficiently specific bounds checking on authorization header could lead to denial of service in the Temporal server on all platforms due to excessive memory allocation.This issue affects all platforms and versions of OSS Server prior to 1.26.3, 1.27.3, and 1.28.1 (i.e., fixed in 1.26.3, 1.27.3, and 1.28.1 and later). Temporal Cloud services are not impacted.

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

The Temporal server has insufficient bounds checking on the authorization header, allowing attackers to trigger excessive memory allocation by sending specially crafted requests with oversized authorization headers, leading to denial of service.

MitigationUpgrade Temporal OSS Server to version 1.26.3, 1.27.3, 1.28.1 or later. Temporal Cloud services are not impacted.

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

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
Authentication
Y
User interaction
None
Scope
N

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L/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:N/AU:Y/R:X/V:X/RE:X/U:X

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. Identify Temporal server installation type
    Determine if running Temporal Cloud or self-hosted Temporal OSS. Temporal Cloud is not affected. Check environment variables, cloud console, or deployment documentation for the installation type.
    Affected if Running self-hosted Temporal OSS Server (not Temporal Cloud)
  2. Check Temporal server version
    Run `tctl --version` or check the container image tag / binary version. For Docker: `docker images | grep temporal`. For Kubernetes: check the deployment image tag. For binary: `./temporal-server --version`.
    Affected if Version is 1.26.0 through 1.26.2, 1.27.0 through 1.27.3, or 1.28.0 (before 1.28.1)
  3. Verify network exposure
    Check if the Temporal server frontend or API port (default 7233) is exposed to untrusted networks or directly to the internet. Review firewall rules, ingress configurations, and network policies.
    Affected if Frontend service is accessible from untrusted networks and version is in the affected range
  4. Check authorization header handling
    Review server logs for signs of large authorization header processing or memory pressure events. Monitor for unusual memory consumption correlated with authenticated API requests.
    Affected if Observing excessive memory allocation during request processing with large authorization headers

You are affected if running self-hosted Temporal OSS Server versions 1.26.0-1.26.2, 1.27.0-1.27.2, or 1.28.0 with the server accessible to network attackers.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade Temporal OSS Server to version 1.26.3, 1.27.3, 1.28.1 or later. Temporal Cloud services are not impacted.

Recommended fix High confidence

Upgrade to Temporal OSS Server 1.28.1 (or later), alternatively 1.27.3 or 1.26.3

  1. 1. Identify the current version of Temporal OSS Server running in your environment
  2. 2. Choose a fixed release version: 1.26.3, 1.27.3, or 1.28.1 (or later) - preferably the latest stable release
  3. 3. Review the Temporal upgrade guide and release notes for your chosen target version
  4. 4. Create a backup of your Temporal configuration and data
  5. 5. Upgrade the Temporal server to the chosen fixed version following standard upgrade procedures
  6. 6. Verify the upgrade was successful and monitor for any issues

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

Have this fixed Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,040
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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-2025-8396 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