CVE-2026-40013
MEDIUMDescription
An attacker that has valid credentials can submit a Sieve script containing an extreme numeric literal, which causes an out-of-bounds write when the ManageSieve service compiles the script. This causes memory corruption and an observed crash of the ManageSieve process, resulting in denial of service for script management. This might be able to be used for remote code execution. Disable the ManageSieve service if users do not need remote Sieve script management. Update to non-vulnerable version. No publicly available exploits are known.
How to fix
No published remediation has been found for this vulnerability's affected products yet.
Mitigation guidance may be in the linked vendor advisories in the References section below.
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CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
Exploit Intelligence
Low risk: more likely to be exploited than 38% of all known CVEs.
References
Related Vulnerabilities
Other CWE-124 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2015-2426 | High | 8.8 | 87% | KEV | - |
| CVE-2023-25610 | Critical | 9.8 | 18% | - | Fix |
| CVE-2018-5388 | Medium | 6.5 | 4.0% | - | Fix |
| CVE-2018-15361 | Critical | 9.8 | 2.9% | - | Fix |
| CVE-2021-36064 | High | 7.8 | 2.7% | - | Fix |
| CVE-2023-48230 | Medium | 5.9 | 1.9% | - | Fix |
Common questions
How do I fix CVE-2026-40013?
No published fix for CVE-2026-40013 has been found yet. Check the linked vendor advisories for guidance as it becomes available.
Is CVE-2026-40013 being actively exploited?
Not that we know of. CVE-2026-40013 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.46% is the estimated probability that it will be exploited in the next 30 days. That is higher than 38% of all scored CVEs.
How severe is CVE-2026-40013?
CVE-2026-40013 has a CVSS v3 base score of 4.3, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-08-28.