When mail_max_userip_connections is set (default 10) and reached, submission-login can crash with epoll() panic caused by file descriptor ha
Noroxi assessment
Priority: Monitor (action score 17/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 0.55% (FIRST EPSS).
- Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
- Fixed version: Open-Xchange GmbH OX Dovecot CE 2.4.5; Open-Xchange GmbH OX Dovecot Pro 2.3.22.2, 3.0.7, 3.1.6.
Low priority for now. Upgrade to Open-Xchange GmbH OX Dovecot CE 2.4.5; Open-Xchange GmbH OX Dovecot Pro 2.3.22.2, 3.0.7, 3.1.6 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
When mail_max_userip_connections is set (default 10) and reached, submission-login can crash with epoll() panic caused by file descriptor handling issues. If running in high-security mode (default for community releases), only the new submission connection gets terminated. If running in high-performance mode (default for Pro releases), all connections handled by the submission-login process will be terminated. The crashes can cause failure for user to send a message, or it can cause duplicate messages to be sent. If TLS is not used (in the backend server processing the submission), duplicate deliveries cannot happen, because the crash can only happen at AUTH stage. Limit the number of connections handled by single submission-login process. This has a performance impact though. Update to non-vulnerable version. No publicly available exploits are known.
- Published
- Aug 28, 2026
- Updated
- Sep 3, 2026
- EPSS
- 0.5% · 45th percentile
- CWE
- CWE-403
Report tools
Action score
17
Monitor
Low priority for now.
- CVSS
- 17 / 40 · 4.3 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.5%
CISA SSVC decision
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- —
- CNA · OX
- 4.3
- NVD has not scored this yet; the score shown is the CNA’s.
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
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Noroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
—
Versions reported by the vendor
Affected version ranges reported by the assigning authority (OX). Independent of NVD's CPE analysis and usually ahead of it.
Open-Xchange GmbH OX Dovecot CE
- 2.3.0 and later · before 2.4.5affected · semver
Open-Xchange GmbH OX Dovecot Pro
- 2.3.0 and later · before 2.3.22.2affected · semver
- 3.0.0 and later · before 3.0.7affected · semver
- 3.1.0 and later · before 3.1.6affected · semver
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| AlmaLinux:10 | dovecot | before 1:2.3.21-19.el10_2.8 | 1:2.3.21-19.el10_2.8 |
| AlmaLinux:10 | dovecot-devel | before 1:2.3.21-19.el10_2.8 | 1:2.3.21-19.el10_2.8 |
| AlmaLinux:10 | dovecot-mysql | before 1:2.3.21-19.el10_2.8 | 1:2.3.21-19.el10_2.8 |
| AlmaLinux:10 | dovecot-pgsql | before 1:2.3.21-19.el10_2.8 | 1:2.3.21-19.el10_2.8 |
| AlmaLinux:10 | dovecot-pigeonhole | before 1:2.3.21-19.el10_2.8 | 1:2.3.21-19.el10_2.8 |
| AlmaLinux:8 | dovecot | before 1:2.3.16-16.el8_10 | 1:2.3.16-16.el8_10 |
| AlmaLinux:8 | dovecot-devel | before 1:2.3.16-16.el8_10 | 1:2.3.16-16.el8_10 |
| AlmaLinux:8 | dovecot-mysql | before 1:2.3.16-16.el8_10 | 1:2.3.16-16.el8_10 |
| AlmaLinux:8 | dovecot-pgsql | before 1:2.3.16-16.el8_10 | 1:2.3.16-16.el8_10 |
| AlmaLinux:8 | dovecot-pigeonhole | before 1:2.3.16-16.el8_10 | 1:2.3.16-16.el8_10 |
| AlmaLinux:9 | dovecot | before 1:2.3.16-18.el9_8.8 | 1:2.3.16-18.el9_8.8 |
| AlmaLinux:9 | dovecot-devel | before 1:2.3.16-18.el9_8.8 | 1:2.3.16-18.el9_8.8 |
| AlmaLinux:9 | dovecot-mysql | before 1:2.3.16-18.el9_8.8 | 1:2.3.16-18.el9_8.8 |
| AlmaLinux:9 | dovecot-pgsql | before 1:2.3.16-18.el9_8.8 | 1:2.3.16-18.el9_8.8 |
| AlmaLinux:9 | dovecot-pigeonhole | before 1:2.3.16-18.el9_8.8 | 1:2.3.16-18.el9_8.8 |
| Alpine:v3.23 | dovecot | before 2.4.5-r0 | 2.4.5-r0 |
| Debian:12 | dovecot | all versions | — |
| Debian:13 | dovecot | before 1:2.4.1+dfsg1-6+deb13u7 | 1:2.4.1+dfsg1-6+deb13u7 |
| Debian:14 | dovecot | before 1:2.4.5+dfsg1-1 | 1:2.4.5+dfsg1-1 |
| openSUSE:Leap 16.0 | dovecot24 | before 2.4.4-160000.2.1 | 2.4.4-160000.2.1 |
| openSUSE:Tumbleweed | dovecot24 | before 2.4.5-1.1 | 2.4.5-1.1 |
| Red Hat:enterprise_linux:10.2 | dovecot | before 1:2.3.21-19.el10_2.8 | 1:2.3.21-19.el10_2.8 |
| Red Hat:enterprise_linux:10.2 | dovecot-debuginfo | before 1:2.3.21-19.el10_2.8 | 1:2.3.21-19.el10_2.8 |
| Red Hat:enterprise_linux:10.2 | dovecot-debugsource | before 1:2.3.21-19.el10_2.8 | 1:2.3.21-19.el10_2.8 |
+32
Same product
open-xchange gmbh: all recordsOther highest-scoring records for the same primary product.
- CVE-2026-42007An attacker that has valid credentials can use a Sieve script with the editheader extension to trigger a use-after-free in the mail editing 36Monitor
- CVE-2026-42391An unauthenticated attacker can send an IMAP ID command with a very large number of parameters before logging in, which causes memory and CP30Monitor
- CVE-2026-33605An unauthenticated attacker can crash the ManageSieve login process by sending a small malformed command before authenticating.30Monitor
- CVE-2026-27852An attacker that can send mail to a user can craft a message whose headers contain a very large number of email addresses or MIME parameters30Monitor
- CVE-2024-23185Very large headers can cause resource exhaustion when parsing message.30Monitor
- CVE-2026-73208An attacker that holds a token intended for a different purpose can authenticate, because when an OAuth2 token response does not contain a s29Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| Open-Xchange GmbH OX Dovecot CE | 2.4.5 | Vendor (CNA) |
| Open-Xchange GmbH OX Dovecot Pro | 2.3.22.2 | Vendor (CNA) |
| Open-Xchange GmbH OX Dovecot Pro | 3.0.7 | Vendor (CNA) |
| Open-Xchange GmbH OX Dovecot Pro | 3.1.6 | Vendor (CNA) |
| almalinux:dovecot | 1:2.3.16-16.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:dovecot-devel | 1:2.3.16-16.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:dovecot-mysql | 1:2.3.16-16.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:dovecot-pgsql | 1:2.3.16-16.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:dovecot-pigeonhole | 1:2.3.16-16.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| alpine:dovecot | 2.4.5-r0 · Alpine:v3.23 | Package registry (OSV) |
| debian:dovecot | 1:2.4.1+dfsg1-6+deb13u7 · Debian:13 | Package registry (OSV) |
| opensuse:dovecot24 | 2.4.5-1.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| red hat:dovecot | 1:2.3.16-16.el8_10 · Red Hat:enterprise_linux:8::appstream | Package registry (OSV) |
| red hat:dovecot-debuginfo | 1:2.3.16-16.el8_10 · Red Hat:enterprise_linux:8::appstream | Package registry (OSV) |
| red hat:dovecot-debugsource | 1:2.3.16-16.el8_10 · Red Hat:enterprise_linux:8::appstream | Package registry (OSV) |
| red hat:dovecot-devel | 1:2.3.16-16.el8_10 · Red Hat:enterprise_linux:8::crb | Package registry (OSV) |
| red hat:dovecot-mysql | 1:2.3.16-16.el8_10 · Red Hat:enterprise_linux:8::appstream | Package registry (OSV) |
| red hat:dovecot-mysql-debuginfo | 1:2.3.16-16.el8_10 · Red Hat:enterprise_linux:8::appstream | Package registry (OSV) |
| red hat:dovecot-pgsql | 1:2.3.16-16.el8_10 · Red Hat:enterprise_linux:8::appstream | Package registry (OSV) |
| red hat:dovecot-pgsql-debuginfo | 1:2.3.16-16.el8_10 · Red Hat:enterprise_linux:8::appstream | Package registry (OSV) |
| red hat:dovecot-pigeonhole | 1:2.3.16-16.el8_10 · Red Hat:enterprise_linux:8::appstream | Package registry (OSV) |
| red hat:dovecot-pigeonhole-debuginfo | 1:2.3.16-16.el8_10 · Red Hat:enterprise_linux:8::appstream | Package registry (OSV) |
| rocky linux:dovecot | 1:2.3.16-16.el8_10 · Rocky Linux:8 | Package registry (OSV) |
| suse:dovecot23 | 2.3.21.1-150200.76.1 · SUSE:Linux Enterprise Module for Server Applications 15 SP7 | Package registry (OSV) |
| suse:dovecot24 | 2.4.4-160000.2.1 · SUSE:Linux Enterprise Server 16.0 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- A low-privileged account is enough.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- none
- Integrity
- none
- Availability
- low · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- None
- Availability impact
- Low
Weakness class (CWE)
CWE-403 · Exposure of File Descriptor to Unintended Control Sphere ('File Descriptor Leak')CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
nvd-secondary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Vendor advisories and official records. Exploit/PoC links are deliberately left out.