Unrated

Denial of Service in GitLab CE/EE CSV import

IdentifiersCVE-2026-1403CWE-20

CVE-2026-1403 is a medium-severity denial-of-service vulnerability in GitLab Community Edition and Enterprise Edition CSV import handling. According to the provided context, the flaw is caused by improper validation of CSV file structure during import processing. A crafted CSV file can trigger failures in background processing and cause Sidekiq workers to crash or become disrupted while handling the import job. The issue 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.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation allows an authenticated user to cause denial of service against GitLab background job processing by disrupting or crashing Sidekiq workers during CSV import. This can interrupt asynchronous platform functionality dependent on Sidekiq, degrade service availability, and potentially delay or prevent processing of queued background tasks.

Mitigation

If you can’t patch tonight, do this now.

If immediate patching is not possible, reduce exposure by restricting CSV import capability to trusted users, monitoring Sidekiq worker stability and job failures, and applying operational controls around file import workflows. However, no complete mitigation is provided in the source context; upgrading to a fixed version is the primary mitigation.

Remediation

Patch, then assume compromise.

Upgrade GitLab CE/EE to a fixed release. The provided context states that GitLab remediated this issue in versions 18.8.9, 18.9.5, and 18.10.3. GitLab strongly recommended immediate upgrades for self-managed installations. GitLab.com was already patched, and GitLab Dedicated customers did not need to take action.

PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

ACTIVITY FEED

Recent activity

4 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

4 SOURCESView more in app

thecyberexpress com vulnerabilitiesNews

Apr 10, 2026

GitLab Security Update Fixes CVE-2026-5173 Flaw

A GitLab CSV import vulnerability that allows authenticated users to disrupt Sidekiq workers, causing denial of service.

cyber security newsNews

Apr 9, 2026

GitLab Patches Multiple Vulnerabilities That Enables DoS and Code Injection Attacks

A medium-severity GitLab vulnerability where weak CSV validation can let an authenticated user crash Sidekiq background workers during file import.

gitlab releasesNews

Apr 8, 2026

GitLab Patch Release: 18.10.3, 18.9.5, 18.8.9 | GitLab

A denial-of-service vulnerability in GitLab CE/EE CSV import handling that could let an authenticated user disrupt Sidekiq workers through malformed CSV structure.

docs gitlabNews

Oct 1, 2018

GitLab Patch Release: 18.10.3, 18.9.5, 18.8.9 | GitLab Docs

A denial-of-service vulnerability in GitLab CSV import that could let an authenticated user disrupt Sidekiq workers via malformed CSV structure.

What this page doesn’t show

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Exposure mapping

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Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity