6.5

CVE-2025-5986: mozilla thunderbird

CVSS: 6.5v3.1MediumModified
AliasesSUSE-SU-2025:02158-1UBUNTU-CVE-2025-5986DEBIAN-CVE-2025-5986
Published 11-06-2025Last modified 13-04-2026
Open JSON

Vulnerability summary

CVE-2025-5986 is a medium (CVSS 6.5) vulnerability in mozilla thunderbird. EPSS estimates a 0.58% chance of exploitation in the next 30 days, higher than 46.6% of scored vulnerabilities.

Overall risk
26/100
0100
Medium · default modelHow is this calculated?
CVSS score
6.5/10
010
Medium · v3.1 (CVE.org)
EPSS score
0.58%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 14 · Related 1
DLA-4239-1DSA-5959-1MGASA-2025-0197RHSA-2025:10159RHSA-2025:10160RHSA-2025:10161

Timeline

  1. 11-06-2025
    PublishedVulnerability first disclosed.
  2. 13-04-2026
    Last modifiedVulnerability information updated.

Description

A crafted HTML email using mailbox:/// links can trigger automatic, unsolicited downloads of .pdf files to the user's desktop or home directory without prompting, even if auto-saving is disabled. This behavior can be abused to fill the disk with garbage data (e.g. using /dev/urandom on Linux) or to leak Windows credentials via SMB links when the email is viewed in HTML mode. While user interaction is required to download the .pdf file, visual obfuscation can conceal the download trigger. Viewing the email in HTML mode is enough to load external content. This vulnerability was fixed in Thunderbird 128.11.1 and Thunderbird 139.0.2.

CVSS metrics

4 scores · 4 sources · 1 version

EPSS trend

Probability

0.58%

Chance of exploitation in the next 30 days

Percentile

47%

Versus all other CVEs

30-day change

0.00 pp

From 0.58% on 19-09-2026

19-09-202619-10-2026
EPSS score
0.58%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Suse4 products
  • MozillaThunderbird&distro=SUSE Linux Enterprise Module for Package Hub 15 SP6< 128.11.1-150200.8.224.1
  • MozillaThunderbird&distro=SUSE Linux Enterprise Module for Package Hub 15 SP7< 128.11.1-150200.8.224.1
  • MozillaThunderbird&distro=SUSE Linux Enterprise Workstation Extension 15 SP6< 128.11.1-150200.8.224.1
  • MozillaThunderbird&distro=SUSE Linux Enterprise Workstation Extension 15 SP7< 128.11.1-150200.8.224.1
Opensuse2 products
  • MozillaThunderbird&distro=openSUSE Leap 15.6< 128.11.1-150200.8.224.1
  • MozillaThunderbird&distro=openSUSE Tumbleweed< 128.11.1-2.1
Debian1 product
  • thunderbird< 1:128.12.0esr-1~deb12u1 | < 1:128.12.0esr-1
Mozilla1 product
Ubuntu1 product
  • thunderbird< 1:128.12.0+build1-0ubuntu0.22.04.1

5 vendors · 9 products

References

12 links
Show all 12 references