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VulnerabilityPublished

CVE-2026-5199: temporal · Insecure Direct Object Reference

Affects temporalSource CVE Database V5

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Not known to be exploited · CVSS 2.3 Low : upgrade to 1.30.3 or 1.29.5 when convenient.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 4.0 base score
2.3Low
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.3% chance of exploitation in 30 days – higher than 26% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 1.30.3, 1.29.5
CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:L/SA:L/S:N/AU:Y/R:U/RE:M

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 1 Apr 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Upgrade temporal to 1.30.3 or 1.29.5.

Affected software

ProductAffectedFixed in
Temporal Technologies, Inc.temporalAffected
  • >=1.30.0 <1.30.3
Fixed in
  • 1.30.3
Temporal Technologies, Inc.temporalAffected
  • >=1.29.0 <1.29.5
Fixed in
  • 1.29.5
GitHubtemporalio/temporalpkg:github/temporalio/temporalOther threatsAffected
  • =1.29.0
  • =1.30.0
Fixed in–
GitHubtemporalpkg:github/temporalOther threatsAffected
  • >=1.29.0 <1.29.5
  • >=1.30.0 <1.30.3
Fixed in
  • 1.29.5
  • 1.30.3

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

If you cannot patch yet, administrators should review and restrict server configurations that allow cross-namespace authorization among internal components, such as disabling or tightly controlling the internal-frontend service or equivalent TLS-based authorization mechanisms. Implement strict namespace isolation policies and limit writer role assignments to trusted users only. Monitor workflow operations for unusual signaling, deletion, or reset activities that could indicate exploitation attempts. Employ network segmentation and access controls to reduce the risk of unauthorized namespace access. For Temporal Cloud users, coordinate with the service provider to understand cell-sharing configurations and request mitigation or isolation if possible. Additionally, enforce strong workflow ID and signal name management to reduce the likelihood of guessing or discovery by attackers. Regularly audit namespace permissions and internal service configurations to ensure adherence to the principle of least privilege.

Description

A writer role user in an attacker-controlled namespace could signal, delete, and reset workflows or activities in a victim namespace on the same cluster. Exploitation requires the attacker to know or guess specific victim workflow ID(s) and, for signal operations, signal names. This was due to a bug introduced in Temporal Server v1.29.0 which inadvertently allowed an attacker to control the namespace name value instead of using the server's own trusted name value within the batch activity code. The batch activity validated the namespace ID but did not cross-check the namespace name against the worker's bound namespace, allowing the per-namespace worker's privileged credentials to operate on an arbitrary namespace. Exploitation requires a server configuration where internal components have cross-namespace authorization, such as deployment of the internal-frontend service or equivalent TLS-based authorization for internal identities. This vulnerability also impacted Temporal Cloud when the attacker and victim namespaces were on the same cell, with the same preconditions as self-hosted clusters.

References

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