CVE-2021-39220: nextcloud mail Improper Input Validation
Vulnerability summary
CVE-2021-39220 is a low (CVSS 3.5) Improper Input Validation vulnerability in nextcloud mail. EPSS estimates a 0.91% chance of exploitation in the next 30 days, higher than 59.3% of scored vulnerabilities.
Timeline
- 25-10-2021PublishedVulnerability first disclosed.
- 04-08-2024Last modifiedVulnerability information updated.
Description
Nextcloud is an open-source, self-hosted productivity platform The Nextcloud Mail application prior to versions 1.10.4 and 1.11.0 does by default not render images in emails to not leak the read state or user IP. The privacy filter failed to filter images with a relative protocol. It is recommended that the Nextcloud Mail application is upgraded to 1.10.4 or 1.11.0. There are no known workarounds aside from upgrading.
CVSS metrics
3 scores · 2 sources · 2 versions- NVDNIST3.5LowCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:N
EPSS trend
Probability
0.91%
Chance of exploitation in the next 30 days
Percentile
59%
Versus all other CVEs
30-day change
+0.13 pp
From 0.78% on 19-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-20Improper Input ValidationThe product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
- CWE-200Exposure of Sensitive Information to an Unauthorized ActorThe product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.
Affected systems
Nextcloud2 products
- mail< 1.10.4
- security-advisories< 1.11.0
1 vendor · 2 products
References
3 links- github.com/nextcloud/security-advisories/security/advisories/GHSA-6q9v-wm8r-rcv5X Refsource CONFIRMThird Party Advisory