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🛡️ CVE-2026-27851 on Ubuntu — dovecot

⚪ Unknown ✅ No Known Exploit OSV
N/A
CVSS Score
0 Low4 Medium7 High9 Critical10

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.

Distribution advisory

This page covers CVE-2026-27851 as tracked by Ubuntu, for the package dovecot. The fix is available in version 1:2.4.2+dfsg1-3ubuntu2.1; earlier versions remain affected.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity high, availability none.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: None — an unauthenticated stranger can try it.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: High — total loss, or loss the attacker controls.
  • Integrity impact: High — total loss, or loss the attacker controls.
  • Availability impact: None.

Weakness class

UBUNTU-CVE-2026-27851 is classified as CWE-235: Improper Handling of Extra Parameters. The product does not handle or incorrectly handles when the number of parameters, fields, or arguments with the same name exceeds the expected amount.

Affected software

UBUNTU-CVE-2026-27851 is recorded against 1 package.

  • dovecot (fixed in 1:2.4.2+dfsg1-3ubuntu2.1)

Timeline and source

Published on 12 May 2026 and last revised on 30 June 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

ubuntu.com (Report)
www.cve.org (Report)
www.openwall.com (Report)
ubuntu.com (Advisory)

Other advisories for this package

dovecot has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-235: Improper Handling of Extra Parameters) in other software:

CVE-2026-27851 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity Unknown
CVSS Score N/A
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CWE N/A
Public Exploit ✅ No
Source OSV
Published 2026-05-12
Updated 2026-08-20
Modified 2026-06-30
Fix URL N/A

Affected Packages

Software From version Fixed in
dovecot — 1:2.4.2+dfsg1-3ubuntu2.1

Site Security Check

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ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

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