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HighPublic exploit

GitLab CE/EE Markdown Preview CPU Exhaustion DoS

IdentifiersCVE-2026-1456CWE-400

GitLab Community Edition (CE) and Enterprise Edition (EE) contain a denial-of-service vulnerability in markdown preview processing. According to the provided content, an unauthenticated attacker can submit specially crafted markdown files that trigger exponential processing during markdown preview, resulting in excessive CPU consumption. The issue affects GitLab CE/EE all versions from 18.7 before 18.7.4 and 18.8 before 18.8.4.

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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 unauthenticated attacker to consume excessive CPU resources on the GitLab instance, degrading performance and potentially causing denial of service or service unavailability for legitimate users. The impact is limited to availability based on the provided information.

Mitigation

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

If immediate patching is not possible, reduce exposure of markdown preview/rendering functionality to untrusted or unauthenticated users where feasible, such as restricting public access, requiring authentication, and applying rate limiting or WAF protections to markdown preview-related endpoints. Monitor for abnormal CPU spikes and suspicious markdown preview activity indicative of exploitation attempts.

Remediation

Patch, then assume compromise.

Upgrade GitLab CE/EE to a fixed version. The provided advisory states that users should upgrade to 18.7.4 or later in the 18.7 series, or 18.8.4 or later in the 18.8 series. The broader release information also references 18.6.6 as a security release, but the specific affected-version statement for this CVE identifies 18.7 before 18.7.4 and 18.8 before 18.8.4.
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.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType
GitLabGitlabapplication

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

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
What this page doesn’t show

The version that knows your environment.

This page is what’s public. Mallory adds the parts that aren’t: which of your assets are affected, which adversaries are exploiting it right now, which detections to deploy, and what to do tonight.
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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 activity2

Community discussion across Reddit, Mastodon, and other social sources.

EXTERNAL REFERENCES
MITRE CVE
cve.org · CVE-2026-1456
NVD
nvd.nist.gov/vuln/detail/CVE-2026-1456
MITRE CWE · CWE-400
cwe.mitre.org
Vendor Advisory
about.gitlab.com/releases/2026/02/10/patch-release-gitlab-18-8-4-released
Permissions Required
hackerone.com/reports/3517928