common/session.c in Claws Mail before 3.17.6 has a protocol violation because suffix data after STARTTLS is mishandled.
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for the hundreds of thousands of vulnerabilities in the database; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for help- Published
- Jul 23, 2020
- Updated
- Jun 16, 2026
- EPSS
- 2.6% · 85th percentile
- CWE
- —
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Report tools
Action score
40
Plan
Add it to your regular patch cycle.
- CVSS
- 39 / 40 · 9.8 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 1 / 30 · 2.6%
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| claws-mail | claws-mail | cpe:2.3:a:claws-mail:claws-mail |
| fedoraproject | fedora | cpe:2.3:o:fedoraproject:fedora |
| opensuse | backports sle | cpe:2.3:a:opensuse:backports_sle |
| opensuse | leap | cpe:2.3:o:opensuse:leap |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- claws-mail claws-mailbefore 3.17.6
- fedoraproject fedora31
- fedoraproject fedora32
- opensuse backports sle15.0
- opensuse leap15.1
- opensuse leap15.2
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | claws-mail | before 3.17.6-1 | 3.17.6-1 |
| openSUSE:Leap 15.1 | claws-mail | before 3.17.3-lp151.2.3.1 | 3.17.3-lp151.2.3.1 |
| openSUSE:Leap 15.2 | claws-mail | before 3.17.6-lp152.3.3.1 | 3.17.6-lp152.3.3.1 |
| openSUSE:Tumbleweed | claws-mail | before 4.0.0-2.5 | 4.0.0-2.5 |
| SUSE:Package Hub 15 SP1 | claws-mail | before 3.17.8-bp152.3.6.1 | 3.17.8-bp152.3.6.1 |
| SUSE:Package Hub 15 SP1 | claws-mail | before 3.17.8-bp152.3.6.1 | 3.17.8-bp152.3.6.1 |
| SUSE:Package Hub 15 SP1 | claws-mail | before 3.17.3-bp151.3.3.1 | 3.17.3-bp151.3.3.1 |
| SUSE:Package Hub 15 SP2 | claws-mail | before 3.18.0-bp153.2.3.1 | 3.18.0-bp153.2.3.1 |
| SUSE:Package Hub 15 SP2 | claws-mail | before 3.17.6-bp152.3.3.1 | 3.17.6-bp152.3.3.1 |
| SUSE:Package Hub 15 SP2 | claws-mail | before 3.18.0-bp153.2.3.1 | 3.18.0-bp153.2.3.1 |
Same product
claws-mail: all recordsOther highest-scoring records for the same primary product.
- CVE-2020-16094In imap_scan_tree_recursive in Claws Mail through 3.17.6, a malicious IMAP server can trigger stack consumption because of unlimited recursi31Monitor
- CVE-2015-8614Multiple stack-based buffer overflows in the (1) conv_jistoeuc, (2) conv_euctojis, and (3) conv_sjistoeuc functions in codeconv.c in Claws M30Monitor
- CVE-2015-8708Stack-based buffer overflow in the conv_euctojis function in codeconv.c in Claws Mail 3.13.1 allows remote attackers to have unspecified imp29Monitor
- CVE-2014-2576plugins/rssyl/feed.c in Claws Mail before 3.10.0 disables the CURLOPT_SSL_VERIFYHOST check for CN or SAN host name fields, which makes it ea28Monitor
- CVE-2021-37746textview_uri_security_check in textview.c in Claws Mail before 3.18.0, and Sylpheed through 3.7.0, does not have sufficient link checks befo24Monitor
- CVE-2012-4507The strchr function in procmime.c in Claws Mail (aka claws-mail) 3.8.1 allows remote attackers to cause a denial of service (NULL pointer de21Monitor
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 |
|---|---|---|
| debian:claws-mail | 3.17.6-1 · Debian:12 | Package registry (OSV) |
| opensuse:claws-mail | 3.17.3-lp151.2.3.1 · openSUSE:Leap 15.1 | Package registry (OSV) |
| opensuse:claws-mail | 3.17.8-bp152.3.6.1 · openSUSE:Leap 15.1 | Package registry (OSV) |
| suse:claws-mail | 3.17.6-bp152.3.3.1 · SUSE:Package Hub 15 SP2 | Package registry (OSV) |
| suse:claws-mail | 3.17.8-bp152.3.6.1 · SUSE:Package Hub 15 SP1 | 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.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
—
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- lists.opensuse.org/opensuse-security-announce/2020-07/msg00090.html
- lists.opensuse.org/opensuse-security-announce/2020-08/msg00002.html
- lists.opensuse.org/opensuse-security-announce/2020-08/msg00060.html
- lists.opensuse.org/opensuse-security-announce/2020-09/msg00051.html
- lists.opensuse.org/opensuse-security-announce/2020-11/msg00013.html
- git.claws-mail.org/?p=claws.git%3Ba=blob%3Bf=RELEASE_NOTES
- git.claws-mail.org/?p=claws.git%3Ba=commit%3Bh=fcc25329049b6f9bd8d890f1197ed61eb12e14d5
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/6YVQB7NRBHO67Q74RS7RZCMW4ENRVBB4/
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/G7UX65342HRVDQML4G4GEVEUB764EUM5/
- security.gentoo.org/glsa/202007-56
Vendor advisories and official records. Exploit/PoC links are deliberately left out.