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CVE-2026-121753VulnerabilityPublished

ZDI-26-872: (0Day) Ashlar-Vellum Cobalt XE File Parsing Use-After-Free Remote Code Execution Vulnerability

Source Zero Day Initiative

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Not known to be exploited.

Data as of 4 Nov 2026, 14:44 UTC

Severity
High

Rated High by Zero Day Initiative · CVSS not yet scored by NVD

Exploitation evidence

  1. Disclosed: evidence found.

    Public on cve.org; its publication date is not in this record

  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 4 Nov 2026.

What to do

AI-suggested

Users should exercise caution when opening files or visiting web pages from untrusted sources. Monitor vendor advisories for updates and apply official patches once released.

Description

A use-after-free vulnerability in Ashlar-Vellum Cobalt XE file parsing allows remote attackers to execute arbitrary code. Exploitation requires user interaction, such as opening a malicious file or visiting a malicious page. The vulnerability has a high severity rating of 7.8 assigned by ZDI.

References

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