CVE Intelligence
Critical

CVE-2026-27851 — When safe filter is used with variable expansion, all following pipelines on the same…

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.

Published May 12, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: OX

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 0.6% (30-day exploitation probability)+7
  • Technical severity (critical)+10

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
0.58%
ahead of 46% of scored CVEs · Oct 15, 2026
Affects
Dovecot
Dovecot and 1 more
CVSS base
9.1
Critical · 4 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation
None
none · proof-of-concept · active
Automatable
No
can an attacker script the kill-chain steps
Technical impact
Total
partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Dovecot Dovecot, Open-Xchange GmbH Dovecot, Open-Xchange GmbH OX Dovecot Pro).
  2. The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
  3. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
  4. Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Dovecot Dovecot < 2.4.4 Vulnerable NIST National Vulnerability Database
Open-Xchange GmbH Dovecot < 3.1.5 Vulnerable NIST National Vulnerability Database
Open-Xchange GmbH OX Dovecot Pro ≤ 3.1.4≤ 2.4.3 Vulnerable CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
9.1 CVSS 3.1 Critical 3.9 5.2 nvd@nist.gov via NIST National Vulnerability Database
7.4 CVSS 3.1 High 2.2 5.2 security@open-xchange.com via NIST National Vulnerability Database
7.4 CVSS 3.1 High 2.2 5.2 0b0ca135-0b70-47e7-9f44-1890c2a1c46c via NIST National Vulnerability Database
7.4 CVSS 3.1 High — — OX via CVE Program (cve.org) e CISA ADP
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N (score shown at the top: nvd@nist.gov)
Scoring entities (NIST, CNA, ADP) score independently; each score is shown with its origin. For prioritization we use 9.1 (NVD (NIST)) as a conservative provisional reference — not a definitive official score.

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-235

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 15, 2026 · 3 reading(s) · max 0.58%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
web/proxy/WAF logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first.

  • 2026
  • Affected products added · open-xchange gmbh/ox dovecot pro
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • SSVC assessment updated
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 13, 2026
  • CVSS changed · 9.1
    Oct 13, 2026 · NIST National Vulnerability Database
  • Source status changed · → Modified
    Oct 13, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 13, 2026 · NIST National Vulnerability Database
  • CVE published
    May 12, 2026 · OX

Source activity

Repeated readings are counted rather than listed.

  • 1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

4 on the record

Elsewhere on this site

Dovecot
every CVE for this vendor
CWE-235
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-73208 Improper Authentication in Open-Xchange GmbH OX Dovecot Pro Aug 28, 2026
  • CVE-2026-73209 Uncontrolled Recursion in Open-Xchange GmbH OX Dovecot Pro Aug 28, 2026
  • CVE-2026-52681 Sieve CPU resource usage is tracked in the compiled script, so an attacker that has… Aug 28, 2026
  • CVE-2026-52687 Uncontrolled Resource Consumption in Open-Xchange GmbH OX Dovecot Pro Aug 28, 2026
  • CVE-2026-42008 Improper Authentication in Open-Xchange GmbH OX Dovecot Pro Aug 28, 2026
  • CVE-2026-42395 Uncontrolled Resource Consumption in Open-Xchange GmbH OX Dovecot Pro Aug 28, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No fixed version, patch or mitigation documented.
  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-27851 is "When safe filter is used with variable expansion, all following pipelines on the same…", rated Critical. It affects Dovecot (Dovecot); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 9.1 describes technical severity. EPSS 0.58% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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