CVE
Ashlar-Vellum Cobalt use-after-free code execution via XE file parsing
- Exploited
- No known exploitation
- Fix
- No fix listed
- Who is exposed
- Specific setups only
- Last modified
- Whether it needs action now or is a reference record, by fixed rules, with why. Last checked is when cve.now last re-read it.What do these mean? →
- Reference
- Last checked
- FIRST's estimate of the chance attackers exploit it in the next 30 days, updated daily.What do these mean? →
- 0.22% · 12th percentile
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 18/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
Ashlar-Vellum Cobalt has a flaw in how it parses XE files that lets an attacker execute arbitrary code in the context of the current process. The attacker reaches it locally without logging in, and a user must open a malicious file or visit a malicious page to trigger it.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
Read the original description
Ashlar-Vellum Cobalt XE File Parsing Use-After-Free Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of Ashlar-Vellum Cobalt. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file.
The specific flaw exists within the parsing of XE files. The issue results from the lack of validating the existence of an object prior to performing operations on the object. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-28757.
Who should check
Teams running Ashlar-Vellum Cobalt, including users who open XE files from outside sources.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure5/25Specific setups only
- Reach?/20Unknown. No tracked technology or package matched
- Severity7.8/10CVSS 7.8
- No patch5/5No patch listed yet
What would change the score
- Would score about 68 if added to CISA KEV
- Would score about 63 if CISA's SSVC rates exploitation active
- Would score about 28 if CISA's SSVC rates it automatable
Check your systems with an agent
Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.
Check whether my systems are affected by CVE-2026-121742 (Ashlar-Vellum Cobalt XE File Parsing Use-After-Free Remote Code Execution Vulnerability), using the cve.now data below.
Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.
What cve.now has for CVE-2026-121742 (entry last updated 2026-11-12):
Affected:
- Ashlar-Vellum Cobalt: versions 1204.209
Fixed versions: none listed yet.
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
Attacker needs: local access, no login, a user action.
CISA KEV: CVE-2026-121742 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-121742 only. If you also check another CVE, look up its own KEV status; never assume it from this one.
How to check:
- Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory.
Verify against the linked advisories before concluding, and cite the date you read each one:
- https://www.zerodayinitiative.com/advisories/ZDI-26-874/
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.
Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.
Entry: https://cve.now/CVE-2026-121742
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-121742"}.Timeline
- CVE published
- First seen by cve.now
Affected versions
- Ashlar-Vellum Cobalt
1204.209
Evidence 3
CVE record · 2
Establishes: The identifier and description.
- Record
- Record
Other links · 1
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-121742
Is CVE-2026-121742 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
Which versions are affected by CVE-2026-121742?
Cobalt: version 1204.209.Source: cve.now feed data