How severe is CVE-2026-27851?

CVE-2026-27851 has a CVSS 3.x base score of 7.4, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2026-27851 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (33rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-27851?

CVE-2026-27851 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-2026-27851?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-27851 have an EU (EUVD) identifier?

Yes. CVE-2026-27851 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-29467.

When was CVE-2026-27851 published?

CVE-2026-27851 was published on 2026-05-12 and last updated on 2026-06-30.

CVE-2026-27851

CVE-2026-27851 is a high-severity vulnerability in Open-xchange Dovecot with a CVSS 3.x base score of 7.4. 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-235.

Key facts

Severity: High (CVSS 3.x base score 7.4)
EPSS exploit prediction: 0% (33rd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-29467
Weakness: CWE-235
Affected product: Open-xchange Dovecot
Published: 2026-05-12
Last modified: 2026-06-30

Description

When safe filter is used with variable expansion, all following pipelines on the same string are incorrectly interpreted as safe too, enabling unsafe data to be unescaped. This can enable SQL / LDAP injection attacks when used in authentication. Avoid using safe filter until on fixed version. No publicly available exploits are known.

Frequently asked questions

What is CVE-2026-27851?: When safe filter is used with variable expansion, all following pipelines on the same string are incorrectly interpreted as safe too, enabling unsafe data to be unescaped. This can enable SQL / LDAP injection attacks when used in authentication. Avoid using safe filter until on fixed version. No publicly available exploits are known.
How severe is CVE-2026-27851?: CVE-2026-27851 has a CVSS 3.x base score of 7.4, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2026-27851 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (33rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-27851?: CVE-2026-27851 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-2026-27851?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-27851 have an EU (EUVD) identifier?: Yes. CVE-2026-27851 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-29467.
When was CVE-2026-27851 published?: CVE-2026-27851 was published on 2026-05-12 and last updated on 2026-06-30.

References

Affected products (2)

cpe:2.3:a:dovecot:dovecot:*:*:*:*:*:*:*:*
cpe:2.3:a:open-xchange:dovecot:*:*:*:*:pro:*:*:*

More vulnerabilities in Open-xchange Dovecot

CVE-2026-24031 — High (CVSS 7.7): Dovecot SQL based authentication can be bypassed when auth_username_chars is cleared by admin. This vulnerability…
CVE-2026-27858 — High (CVSS 7.5): Attacker can send a specifically crafted message before authentication that causes managesieve to allocate large amount…
CVE-2025-59032 — High (CVSS 7.5): ManageSieve AUTHENTICATE command crashes when using literal as SASL initial response. This can be used to crash…
CVE-2026-27856 — High (CVSS 7.4): Doveadm credentials are verified using direct comparison which is susceptible to timing oracle attack. An attacker can…
CVE-2026-33603 — Medium (CVSS 6.8): Attacker can use a specially crafted base64 exchange between Dovecot and Client to fake SCRAM TLS channel binding. This…
CVE-2026-27855 — Medium (CVSS 6.8): Dovecot OTP authentication is vulnerable to replay attack under specific conditions. If auth cache is enabled, and…

All CVEs affecting Open-xchange Dovecot →

Other CWE-235 vulnerabilities

CVE-2026-20083 — Medium (CVSS 6.5): A vulnerability in the Secure Copy Protocol (SCP) server feature of Cisco IOS XE Software could allow an authenticated,…
CVE-2024-47651 — Medium (CVSS 6.5): This vulnerability exists in Shilpi Client Dashboard due to improper handling of multiple parameters in the API…
CVE-2017-20160 — Medium (CVSS 6.3): A vulnerability was found in flitto express-param up to 0.x. It has been classified as critical. This affects an…

Browse all CWE-235 vulnerabilities →