How severe is CVE-2020-16094?

CVE-2020-16094 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2020-16094 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (76th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-16094?

CVE-2020-16094 primarily affects Claws-mail. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-16094?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2020-16094 published?

CVE-2020-16094 was published on 2020-07-28 and last updated on 2026-06-17.

CVE-2020-16094

CVE-2020-16094 is a high-severity vulnerability in Claws-mail with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-674.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 2% (76th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-674
Affected product: Claws-mail
Published: 2020-07-28
Last modified: 2026-06-17

Description

In imap_scan_tree_recursive in Claws Mail through 3.17.6, a malicious IMAP server can trigger stack consumption because of unlimited recursion into subdirectories during a rebuild of the folder tree.

Frequently asked questions

What is CVE-2020-16094?: In imap_scan_tree_recursive in Claws Mail through 3.17.6, a malicious IMAP server can trigger stack consumption because of unlimited recursion into subdirectories during a rebuild of the folder tree.
How severe is CVE-2020-16094?: CVE-2020-16094 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2020-16094 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (76th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-16094?: CVE-2020-16094 primarily affects Claws-mail. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-16094?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2020-16094 published?: CVE-2020-16094 was published on 2020-07-28 and last updated on 2026-06-17.

References

Affected products (4)

cpe:2.3:a:claws-mail:claws-mail:*:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:31:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*

More vulnerabilities in Claws-mail

CVE-2020-15917 — Critical (CVSS 9.8): common/session.c in Claws Mail before 3.17.6 has a protocol violation because suffix data after STARTTLS is mishandled.
CVE-2015-8708 — High (CVSS 7.3): Stack-based buffer overflow in the conv_euctojis function in codeconv.c in Claws Mail 3.13.1 allows remote attackers to…
CVE-2015-8614 — High (CVSS 7.3): Multiple stack-based buffer overflows in the (1) conv_jistoeuc, (2) conv_euctojis, and (3) conv_sjistoeuc functions in…
CVE-2014-2576 — Medium (CVSS 6.8): plugins/rssyl/feed.c in Claws Mail before 3.10.0 disables the CURLOPT_SSL_VERIFYHOST check for CN or SAN host name…
CVE-2021-37746 — Medium (CVSS 6.1): textview_uri_security_check in textview.c in Claws Mail before 3.18.0, and Sylpheed through 3.7.0, does not have…
CVE-2012-4507 — Medium (CVSS 5.0): The strchr function in procmime.c in Claws Mail (aka claws-mail) 3.8.1 allows remote attackers to cause a denial of…

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Other CWE-674 (Uncontrolled Recursion) vulnerabilities

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CVE-2021-41752 — Critical (CVSS 9.8): Stack overflow vulnerability in Jerryscript before commit e1ce7dd7271288be8c0c8136eea9107df73a8ce2 on Oct 20, 2021 due…
CVE-2018-1000618 — Critical (CVSS 9.8): EOSIO/eos eos version after commit f1545dd0ae2b77580c2236fdb70ae7138d2c7168 contains a stack overflow vulnerability in…
CVE-2025-10728 — Critical (CVSS 9.4): When the module renders a Svg file that contains a <pattern> element, it might end up rendering it recursively leading…
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