CVE-2026-40203
When IMAP compression is enabled, the same compression state is reused across responses in a session, so response sizes depend on both attacker-supplied mail and other mail in the same mailbox.
Published Aug 28, 2026 · Updated Sep 3, 2026
The full analysis for this CVE is not ready yet, so this page shows the scores and scope from the public record. How CVEs are selected
Key Facts
Routine patching- CVE-2026-40203 is a low-severity vulnerability (CVSS 3.7).
- It is not listed in any known-exploited vulnerabilities catalog. No public exploit code is known.
- No fixed version is listed yet; check the vendor advisory for mitigations.
- Brandefense priority: routine patching, as no exploitation is known and its severity is moderate or low.
Scores
CVSS
3.7
EPSS (30-day exploit likelihood)
n/a
Exploit maturity
None known
ATLAS score
n/a
Outside the curated set
FAQ
Common Questions.
When IMAP compression is enabled, the same compression state is reused across responses in a session, so response sizes depend on both attacker-supplied mail and other mail in the same mailbox.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
No public exploit code is known.
No fixed version is listed yet; check the vendor advisory for mitigations.
Brandefense priority: routine patching, as no exploitation is known and its severity is moderate or low.
Is CVE-2026-40203 On Your Attack Surface?
Brandefense matches it against the products discovered on your perimeter and opens a finding the day a CVE like this is listed.
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