Description
A malicious, compromised, or MITM-controlled Exchange server can return a single well-formed SOAP response containing an element with enough attributes to keep Thunderbird's main thread CPU-bound for seconds to hours. This vulnerability was fixed in Thunderbird 158 and Thunderbird 153.5.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Mozilla | Thunderbird | — | 153.5 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | thunderbird | 1:153.5.0esr-1 | — |
| Debian 13 | thunderbird | 1:153.5.1esr-1~deb13u1 | — |
| Debian 12 | thunderbird | 1:153.5.1esr-1~deb12u1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | thunderbird | No fix yet | — |
| Ubuntu 26.04 LTS | thunderbird | No fix yet | — |
| Ubuntu 24.04 LTS | thunderbird | No fix yet | — |
| Ubuntu 22.04 LTS | thunderbird | No fix yet | — |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | MozillaThunderbird | 153.5.0-150400.13.9.1 | SUSE-SU-2026:4736-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | MozillaThunderbird | 153.5.1-1.1 | openSUSE-SU-2026:12224-1 |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2 | thunderbird | 153.5.1-1.amzn2.0.1 | ALAS2-2026-4057 |
Advisories 4
- WID-SEC-2026-3942 Mozilla Firefox und Thunderbrid: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 11, 2026
- ALAS2-2026-4057 Important: thunderbird security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Nov 2, 2026
- openSUSE-SU-2026:12224-1 MozillaThunderbird-153.5.1-1.1 on GA media SUSE / openSUSE Security Updates · Oct 23, 2026
- SUSE-SU-2026:4736-1 Security update for MozillaThunderbird SUSE / openSUSE Security Updates · Oct 20, 2026