CVE-2026-53296: mailbox: mailbox-test: free channels on probe error

mediumCVSS 5.5CVE-2026-53296

CSIRTS triage

Other

What: The mailbox-test feature has been updated to free channels on probe error.
Who is affected: Deployments using the mailbox-test feature are affected.
Urgency: Remediation is medium urgency due to potential resource management issues.
Action: Apply the update that includes the channel management fix.

AI-assisted analysis generated from the source advisory — verify against the original.

Details

Source: Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity: medium — CVSS 5.5
Published: 2026-06-09
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-53296

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-532960.13% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 3% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-53296	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

Recent advisories for mailbox

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

unknownCVE-2026-53296: In the Linux kernel, the following vulnerability has been resolved: mailbox: mailbox-test: fre…nvd · 2026-06-26
unknownCVE-2026-53295: In the Linux kernel, the following vulnerability has been resolved: mailbox: add sanity check …nvd · 2026-06-26
unknownCVE-2026-53294: In the Linux kernel, the following vulnerability has been resolved: mailbox: mailbox-test: don…nvd · 2026-06-26
mediumCVE-2026-53294: mailbox: mailbox-test: don't free the reused channelmsrc · 2026-06-09
mediumCVE-2026-53295: mailbox: add sanity check for channel arraymsrc · 2026-06-09