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PatchSiren cyber security CVE debrief

CVE-2026-55798 python-pillow CVE debrief

AI-assisted PatchSiren debrief based on the supplied source corpus. The CVE record was published on 2026-07-06T19:17:08.830Z and has not been modified since then. The NVD entry is currently Analyzed. This vulnerability affects Pillow, a Python imaging library, on Windows systems. The vulnerability class is related to improper command construction and execution. The likely operational impact includes potential for local attacks and arbitrary command execution.

Vendor
python-pillow
Product
Pillow
CVSS
MEDIUM 4.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-07-06
Original CVE updated
2026-07-07
Advisory published
2026-07-06
Advisory updated
2026-07-07

Who should care

Users of Pillow library on Windows systems, operators of affected deployments, platform administrators, vulnerability management teams, and security teams should be aware of this vulnerability and take necessary actions to mitigate it.

Technical summary

Pillow is a Python imaging library. Prior to 12.3.0, WindowsViewer.get_command() constructed a cmd.exe shell command by directly embedding a file path into an f-string without escaping and passed the result to subprocess.Popen(..., shell=True), allowing shell metacharacters in the file path to inject arbitrary cmd.exe commands. This issue is fixed in version 12.3.0. Users of Pillow library on Windows systems should update to version 12.3.0 or later to mitigate this vulnerability. The vulnerability has a CVSS score of 4.5 and is classified as MEDIUM severity.

Defensive priority

Medium priority due to CVSS score of 4.5 and potential for local attack.

Recommended defensive actions

  • Update Pillow to version 12.3.0 or later
  • Review and validate file paths used in WindowsViewer.get_command()
  • Implement additional input validation and sanitization for file paths
  • Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
  • 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

Evidence notes

The CVE record and NVD entry provide details on the vulnerability and its fix. Release notes and patch commits are available. The vulnerability allows for arbitrary cmd.exe commands due to improper escaping of file paths in WindowsViewer.get_command(). Users should verify their deployments and review official advisories for affected scope and severity. Defensive measures include updating Pillow to version 12.3.0 or later and implementing additional input validation and sanitization for file paths.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-55798 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-55798

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

  • CVE-2026-55798 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-55798

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

Supplemental references

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.