CVE-2025-8396Network attack vector

Denial of service via authorization-header memory allocation

Published Sep 15, 2025 · Updated Sep 15, 2025

Resource exhaustion in Temporal Technologies Temporal Server allows remote attackers to interrupt affected OSS releases via authorization headers. The default JWT claim mapper applies insufficient bounds checking to an authorization header, permitting excessive memory allocation. Exploitation requires the default claim mapper and exposure to untrusted clients; Temporal Cloud is not affected.

CVSS severity6.9
Medium
EPSS probability0.39%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in Temporal Technologies Temporal Server allows remote attackers to interrupt affected OSS releases via authorization headers. The default JWT claim mapper applies insufficient bounds checking to an authorization header, permitting excessive memory allocation. Exploitation requires the default claim mapper and exposure to untrusted clients; Temporal Cloud is not affected.

The record

CVE
CVE-2025-8396
Published
Sep 15, 2025
Updated
Sep 15, 2025
Vendor
Temporal Technologies
Product
Temporal Server
Classifications
CWE-770, CAPEC-130, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 15, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 15, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <1.26.3
  2. Affected versionversion=1.27.0 <1.27.3
  3. Affected versionversion=1.28.0 <1.28.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Temporal Technologies · Temporal Serverversion=0 <1.26.3; version=1.27.0 <1.27.3; version=1.28.0 <1.28.1

Published CVSS scores

6.9GitHub Advisory DatabaseCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
CAPEC-130Excessive Allocation
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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