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NVD / CVE Program· CNA mitre

CVE-2021-33515: The submission service in Dovecot before 2.3.15 allows STARTTLS command injection in lib-smtp.

MediumCVSS 4.8 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 20/100)

  • 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: 2.8% (FIRST EPSS); higher than 86.8% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. Special conditions such as timing or configuration are required.
  • Fixed version: dovecot (AlmaLinux:8) 1:2.3.16-2.el8; dovecot-devel (AlmaLinux:8) 1:2.3.16-2.el8; dovecot-mysql (AlmaLinux:8) 1:2.3.16-2.el8.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to dovecot (AlmaLinux:8) 1:2.3.16-2.el8; dovecot-devel (AlmaLinux:8) 1:2.3.16-2.el8; dovecot-mysql (AlmaLinux:8) 1:2.3.16-2.el8 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

The submission service in Dovecot before 2.3.15 allows STARTTLS command injection in lib-smtp. Sensitive information can be redirected to an attacker-controlled address.

Published
Jun 28, 2021
Updated
Jun 16, 2026
EPSS
2.8% · 86th percentile

Report tools

JSON

Action score

20

Monitor

Low priority for now.

CVSS
19 / 40 · 4.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
1 / 30 · 2.8%

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.

Follow CVE-2021-33515

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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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.

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Affected 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.

VendorProduct
dovecotdovecot
fedoraprojectfedora
debiandebian linux

Using dovecot? Add it to your stack and be the first to know about CVEs like this one. (Email server)

Watch new CVEs for dovecot

When you'll hear from us

  • when a new CVE affecting this product is published
  • when a record in your stack enters KEV or is weaponized

One daily email digest (06:00 UTC); connect a webhook for KEV listings and weaponized exploits every 10 minutes on paid plans, on the hour on the free plan.

Your free account also gets you

  • CVE alerts: add the products and versions you run, get the new CVEs that affect them
  • Uptime monitoring: 1 site, instant email when it goes down
  • Add your domain: subdomains and takeover risk scanned every week (1 domain)
  • 10 scans an hour on the security tools, at most 30 a day (3 a day without an account), an API key and MCP
  • All your scans in one panel: findings, what changed in the last scan, a report per domain or per client (PDF, share link)
All free tools

Sign up with email · Have an account? Sign in

Free account, no card. Unfollow any time.

Don't want an account? Get "Exploited this week" by email every Monday

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • dovecot dovecotbefore 2.3.14.1

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
AlmaLinux:8dovecotbefore 1:2.3.16-2.el81:2.3.16-2.el8
AlmaLinux:8dovecot-develbefore 1:2.3.16-2.el81:2.3.16-2.el8
AlmaLinux:8dovecot-mysqlbefore 1:2.3.16-2.el81:2.3.16-2.el8
AlmaLinux:8dovecot-pgsqlbefore 1:2.3.16-2.el81:2.3.16-2.el8
AlmaLinux:8dovecot-pigeonholebefore 1:2.3.16-2.el81:2.3.16-2.el8
Alpine:v3.11dovecotbefore 2.3.15-r02.3.15-r0
Debian:10dovecotbefore 1:2.3.4.1-5+deb10u71:2.3.4.1-5+deb10u7
Debian:12dovecotbefore 1:2.3.13+dfsg1-21:2.3.13+dfsg1-2
openSUSE:Leap 15.2dovecot23before 2.3.11.3-lp152.2.9.12.3.11.3-lp152.2.9.1
openSUSE:Leap 15.3dovecot23before 2.3.11.3-55.12.3.11.3-55.1
Red Hat:enterprise_linux:8::appstreamdovecotbefore 1:2.3.16-2.el81:2.3.16-2.el8
Red Hat:enterprise_linux:8::appstreamdovecot-debuginfobefore 1:2.3.16-2.el81:2.3.16-2.el8
Red Hat:enterprise_linux:8::appstreamdovecot-debugsourcebefore 1:2.3.16-2.el81:2.3.16-2.el8
Red Hat:enterprise_linux:8::appstreamdovecot-mysqlbefore 1:2.3.16-2.el81:2.3.16-2.el8
Red Hat:enterprise_linux:8::appstreamdovecot-mysql-debuginfobefore 1:2.3.16-2.el81:2.3.16-2.el8
Red Hat:enterprise_linux:8::appstreamdovecot-pgsqlbefore 1:2.3.16-2.el81:2.3.16-2.el8
Red Hat:enterprise_linux:8::appstreamdovecot-pgsql-debuginfobefore 1:2.3.16-2.el81:2.3.16-2.el8
Red Hat:enterprise_linux:8::appstreamdovecot-pigeonholebefore 1:2.3.16-2.el81:2.3.16-2.el8
Red Hat:enterprise_linux:8::appstreamdovecot-pigeonhole-debuginfobefore 1:2.3.16-2.el81:2.3.16-2.el8
Red Hat:enterprise_linux:8::crbdovecot-develbefore 1:2.3.16-2.el81:2.3.16-2.el8
Rocky Linux:8dovecotbefore 1:2.3.16-2.el81:2.3.16-2.el8
SUSE:Linux Enterprise High Performance Computing 15 SP1-ESPOSdovecot23before 2.3.11.3-24.12.3.11.3-24.1
SUSE:Linux Enterprise High Performance Computing 15-ESPOSdovecot23before 2.3.11.3-4.35.12.3.11.3-4.35.1
SUSE:Linux Enterprise Module for Server Applications 15 SP2dovecot23before 2.3.11.3-55.12.3.11.3-55.1

Same product

dovecot: all records

Other highest-scoring records for the same primary product.

  • CVE-2019-11500In Dovecot before 2.2.36.4 and 2.3.x before 2.3.7.2 (and Pigeonhole before 0.5.7.2), protocol processing can fail for quoted strings.
    58Plan
  • CVE-2020-7046lib-smtp in submission-login and lmtp in Dovecot 2.3.9 before 2.3.9.3 mishandles truncated UTF-8 data in command parameters, as…
    45Plan
  • CVE-2016-8652The auth component in Dovecot before 2.2.27, when auth-policy is configured, allows a remote attackers to cause a denial of service (crash)…
    37Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2021-29157Jun 28, 2021 · Dovecot before 2.3.15 allows ../ Path Traversal.
    22Monitor
  • ← EarlierCVE-2020-28200Jun 28, 2021 · The Sieve engine in Dovecot before 2.3.15 allows Uncontrolled Resource Consumption, as demonstrated by a situation with a complex regular…
    18Monitor
  • Later →CVE-2022-30550Jul 17, 2022 · An issue was discovered in the auth component in Dovecot 2.2 and 2.3 before 2.3.20.
    36Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
almalinux:dovecot1:2.3.16-2.el8 · AlmaLinux:8Package registry (OSV)
almalinux:dovecot-devel1:2.3.16-2.el8 · AlmaLinux:8Package registry (OSV)
almalinux:dovecot-mysql1:2.3.16-2.el8 · AlmaLinux:8Package registry (OSV)
almalinux:dovecot-pgsql1:2.3.16-2.el8 · AlmaLinux:8Package registry (OSV)
almalinux:dovecot-pigeonhole1:2.3.16-2.el8 · AlmaLinux:8Package registry (OSV)
alpine:dovecot2.3.15-r0 · Alpine:v3.11Package registry (OSV)
debian:dovecot1:2.3.13+dfsg1-2 · Debian:12Package registry (OSV)
opensuse:dovecot232.3.11.3-lp152.2.9.1 · openSUSE:Leap 15.2Package registry (OSV)
red hat:dovecot1:2.3.16-2.el8 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:dovecot-debuginfo1:2.3.16-2.el8 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:dovecot-debugsource1:2.3.16-2.el8 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:dovecot-devel1:2.3.16-2.el8 · Red Hat:enterprise_linux:8::crbPackage registry (OSV)
red hat:dovecot-mysql1:2.3.16-2.el8 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:dovecot-mysql-debuginfo1:2.3.16-2.el8 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:dovecot-pgsql1:2.3.16-2.el8 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:dovecot-pgsql-debuginfo1:2.3.16-2.el8 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:dovecot-pigeonhole1:2.3.16-2.el8 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:dovecot-pigeonhole-debuginfo1:2.3.16-2.el8 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
rocky linux:dovecot1:2.3.16-2.el8 · Rocky Linux:8Package registry (OSV)
suse:dovecot232.3.11.3-4.35.1 · SUSE:Linux Enterprise High Performance Computing 15-ESPOSPackage 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.

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • Special conditions such as timing or configuration are required.

If successful

Confidentiality
low · data can be read
Integrity
low · data or configuration can be modified
Availability
none
Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
Low
Integrity impact
Low
Availability impact
None

Weakness class (CWE)

CWE-77 · Improper Neutralization of Special Elements used in a Command ('Command Injection')

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

References

Show all references (5 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records