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Fencer Intel
medium 5.3

CVE-2025-26695 json

Downloading of OpenPGP keys from WKD used incorrect padding

published last yr. modified 4mo ago also EUVD-2025-7705

cvss
5.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 4%
public exploits
0
none known

Summary

When requesting an OpenPGP key from a WKD server, an incorrect padding size was used and a network observer could have learned the length of the requested email address. This vulnerability was fixed in Thunderbird 136 and Thunderbird 128.8.

Patch / fix

  • mozilla thunderbird 128.8, 136
  • thunderbird Debian 12 1:128.8.0esr-1~deb12u1
  • thunderbird Debian 14, Debian 13 1:128.8.0esr-1

debian advisories DEBIAN-CVE-2025-26695

  • thunderbird Ubuntu 22.04 LTS 1:128.12.0+build1-0ubuntu0.22.04.1

ubuntu advisories UBUNTU-CVE-2025-26695

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • thunderbird RHEL 9 128.8.0-2.el9_5
  • thunderbird RHEL 8 128.8.0-2.el8_10
  • thunderbird RHEL 8.6 TUS, RHEL 8.6 E4S, RHEL 8.6 AUS 128.8.0-2.el8_6
  • thunderbird RHEL 8.4 TUS, RHEL 8.4 E4S, RHEL 8.4 AUS 128.8.0-2.el8_4
  • thunderbird RHEL 9.0 E4S 128.8.0-2.el9_0
  • thunderbird RHEL 8.2 AUS 128.8.0-2.el8_2
  • thunderbird RHEL 8.8 EUS 128.8.0-2.el8_8
  • thunderbird RHEL 9.2 EUS 128.8.0-2.el9_2

red hat advisories RHSA-2025:3036RHSA-2025:3009RHSA-2025:3013RHSA-2025:2960RHSA-2025:2958RHSA-2025:2959

  • MozillaThunderbird SLE Workstation Extension 15 SP6, SLE Module for Package Hub 15 SP6, openSUSE Leap 15.6 128.8.0-150200.8.203.1

suse advisories SUSE-SU-2025:0849-1

  • thunderbird AlmaLinux 8 128.8.0-2.el8_10.alma.1

almalinux advisories ALSA-2025:2900

Is CVE-2025-26695 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-26695 updated cvss 4.3

thunderbird: Downloading of OpenPGP keys from WKD used incorrect padding

  • Red Hat Enterprise Linux 6 thunderbird Red Hat Enterprise Linux 7 thunderbird
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 9 thunderbird-flatpak-container Red Hat Enterprise Linux 10 thunderbird, thunderbird-flatpak-container
    affected: no fix available
  • Red Hat Enterprise Linux AppStream (v. 8) thunderbird 128.8.0-2.el8_10
    fixed: vendor fix RHSA-2025:2900
  • Red Hat Enterprise Linux AppStream (v. 9) thunderbird 128.8.0-2.el9_5
    fixed: vendor fix RHSA-2025:2899
  • Red Hat Enterprise Linux AppStream AUS (v. 8.2) thunderbird 128.8.0-2.el8_2
    fixed: vendor fix RHSA-2025:2960
  • Red Hat Enterprise Linux AppStream AUS (v.8.4) thunderbird 128.8.0-2.el8_4
    fixed: vendor fix RHSA-2025:3009
  • Red Hat Enterprise Linux AppStream AUS (v.8.6) thunderbird 128.8.0-2.el8_6
    fixed: vendor fix RHSA-2025:3036
  • Red Hat Enterprise Linux AppStream E4S (v.8.4) thunderbird 128.8.0-2.el8_4
    fixed: vendor fix RHSA-2025:3009
show 7 more
  • Red Hat Enterprise Linux AppStream E4S (v.8.6) thunderbird 128.8.0-2.el8_6
    fixed: vendor fix RHSA-2025:3036
  • Red Hat Enterprise Linux AppStream E4S (v.9.0) thunderbird 128.8.0-2.el9_0
    fixed: vendor fix RHSA-2025:3013
  • Red Hat Enterprise Linux AppStream EUS (v.8.8) thunderbird 128.8.0-2.el8_8
    fixed: vendor fix RHSA-2025:2958
  • Red Hat Enterprise Linux AppStream EUS (v.9.2) thunderbird 128.8.0-2.el9_2
    fixed: vendor fix RHSA-2025:2959
  • Red Hat Enterprise Linux AppStream EUS (v.9.4) thunderbird 128.8.0-2.el9_4
    fixed: vendor fix RHSA-2025:2957
  • Red Hat Enterprise Linux AppStream TUS (v.8.4) thunderbird 128.8.0-2.el8_4
    fixed: vendor fix RHSA-2025:3009
  • Red Hat Enterprise Linux AppStream TUS (v.8.6) thunderbird 128.8.0-2.el8_6
    fixed: vendor fix RHSA-2025:3036

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
last yr.

Exploit prediction

0.16% chance of exploitation in the next 30 days, higher than 4% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CISA ADP 3.1 5.3 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
CNA 3.1 5.3 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L

Affected products

  • Mozilla Thunderbird

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.