CVE-2026-42006

CVE-2026-42006 is a medium-severity vulnerability in Open-xchange Dovecot with a CVSS 3.x base score of 4.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-400.

Key facts

Description

An attacker can cause uncontrolled memory usage with excessive bracing over IMAP. The fix in CVE-2026-27857 was incomplete, only blocking one way of doing this, so there was still another way left open. In particular, the fix was for closing braces, but you could still use open braces to bypass the limit. Using excessive bracing, attacker can cause memory usage up to configured memory limit. Install fixed version, or configure vsz_limit for imap process to low value. No publicly available exploits are known.

Frequently asked questions

What is CVE-2026-42006?
An attacker can cause uncontrolled memory usage with excessive bracing over IMAP. The fix in CVE-2026-27857 was incomplete, only blocking one way of doing this, so there was still another way left open. In particular, the fix was for closing braces, but you could still use open braces to bypass the limit. Using excessive bracing, attacker can cause memory usage up to configured memory limit. Install fixed version, or configure vsz_limit for imap process to low value. No publicly available exploits are known.
How severe is CVE-2026-42006?
CVE-2026-42006 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.
Is CVE-2026-42006 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (36th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-42006?
CVE-2026-42006 primarily affects Open-xchange Dovecot. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-42006?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-42006 have an EU (EUVD) identifier?
Yes. CVE-2026-42006 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-29473.
When was CVE-2026-42006 published?
CVE-2026-42006 was published on 2026-05-12 and last updated on 2026-06-30.

References

Affected products (2)

More vulnerabilities in Open-xchange Dovecot

All CVEs affecting Open-xchange Dovecot →

Other CWE-400 (Uncontrolled Resource Consumption) vulnerabilities

Browse all CWE-400 (Uncontrolled Resource Consumption) vulnerabilities →