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PatchSiren cyber security CVE debrief

CVE-2026-1403 GitLab CVE debrief

GitLab has remediated an issue in GitLab CE/EE affecting all versions from 11.7 before 18.8.9, 18.9 before 18.9.5, and 18.10 before 18.10.3 that when importing CSV files could have allowed an authenticated user to cause denial of service to Sidekiq workers due to improper validation of CSV file structure. This vulnerability could impact system performance and availability. Defenders should assess exposure and prioritize remediation to prevent potential denial of service to Sidekiq workers.

Vendor
GitLab
Product
Unknown
CVSS
MEDIUM 6.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-10-07
Original CVE updated
2026-10-07
Advisory published
2026-10-07
Advisory updated
2026-10-07

Who should care

Defenders responsible for GitLab deployments, particularly those using versions prior to the patched releases, should assess exposure and prioritize remediation to prevent potential denial of service to Sidekiq workers.

Why it matters

This vulnerability could allow an authenticated user to cause denial of service to Sidekiq workers in GitLab deployments using affected versions, impacting system performance and availability. Defenders should prioritize verifying exposure, assessing impact, and remediating vulnerable systems.

  • Denial of service to Sidekiq workers could impact system performance and availability.
  • Verification of exposure and impact is necessary to prioritize remediation efforts.
  • Remediation requires updating to a patched version of GitLab.

Technical summary

The vulnerability affects GitLab CE/EE versions from 11.7 before 18.8.9, 18.9 before 18.9.5, and 18.10 before 18.10.3. An authenticated user could cause denial of service to Sidekiq workers by importing maliciously crafted CSV files due to improper validation of CSV file structure. This could impact system performance and availability. Defenders should prioritize verifying exposure and assessing the impact of this vulnerability on their systems, particularly those using GitLab versions prior to the patched releases.

Defensive priority

Defenders should prioritize verifying exposure and assessing the impact of this vulnerability on their systems, particularly those using GitLab versions prior to the patched releases.

Recommended defensive actions

  • Verify if the system uses affected GitLab versions and assess the potential impact of denial of service to Sidekiq workers.
  • Update to a patched version of GitLab (18.8.9, 18.9.5, or 18.10.3) to remediate the vulnerability.
  • Monitor Sidekiq worker activity and CSV import functionality for potential abuse.
  • Review compensating controls for exposed systems while remediation is scheduled and verified.
  • Check relevant monitoring, detection, and logs for exposed assets that need extra review.
  • Track exceptions, retest remediated assets, and close the item only after evidence is documented.
  • Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.

Evidence notes

The CVE record and source item provide details on the vulnerability, including its description, affected versions, and references to additional information. The vulnerability affects GitLab CE/EE versions from 11.7 before 18.8.9, 18.9 before 18.9.5, and 18.10 before 18.10.3. An authenticated user could cause denial of service to Sidekiq workers by importing maliciously crafted CSV files due to improper validation of CSV file structure. Evidence is limited to CVE Program and NVD details.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-1403 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-1403

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-1403 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-1403

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • Allocation of Resources Without Limits or Throttling in GitLab

    Unverified legacy reference

    URL: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/1xxx/CVE-2026-1403.json

    cve_program_cvelist_v5

  • Source reference

    Unverified legacy reference

    URL: https://hackerone.com/reports/3328937

    Supplemental source - technical-description, exploit, permissions-required

  • Source reference

    Unverified legacy reference

    URL: https://gitlab.com/gitlab-org/gitlab/-/work_items/587573

    Supplemental source

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.