Description
Syncthing is an open source, continuous file synchronization program. In versions prior to 1.23.5 a compromised instance with shared folders could sync malicious files which contain arbitrary HTML and JavaScript in the name. If the owner of another device looks over the shared folder settings and moves the mouse over the latest sync, a script could be executed to change settings for shared folders or add devices automatically. Additionally adding a new device with a malicious name could embed HTML or JavaScript inside parts of the page. As a result the webUI may be subject to a stored cross site scripting attack. This issue has been addressed in version 1.23.5. Users are advised to upgrade. Users unable to upgrade should avoid sharing folders with untrusted users.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| syncthing | syncthing | < 1.23.5 | — |
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 | syncthing | 1.27.2~ds4-1 | — |
| Debian 13 | syncthing | 1.27.2~ds4-1 | — |
| Debian 12 | syncthing | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | syncthing | No fix yet | — |
| Ubuntu 25.10 | syncthing | No fix yet | — |
| Ubuntu 20.04 LTS | syncthing | No fix yet | — |
| Ubuntu 18.04 LTS | syncthing | No fix yet | — |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 26.04 LTS | syncthing | No fix yet | — |
| Ubuntu Pro 24.04 LTS | syncthing | No fix yet | — |
| Ubuntu Pro 22.04 LTS | syncthing | No fix yet | — |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SUSE Package Hub 15 SP5 | syncthing | 1.23.5-bp155.2.3.1 | openSUSE-SU-2023:0126-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | syncthing | 1.23.5-1.1 | openSUSE-SU-2024:12984-1 |
| openSUSE Leap 15.5 | syncthing | 1.23.5-bp155.2.3.1 | openSUSE-SU-2023:0126-1 |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| Go | github.com/syncthing/syncthing | < 1.23.5 | 1.23.5 | GHSA-9rp6-23gf-4c3h |
Advisories 2
- openSUSE-SU-2023:0126-1 Security update for syncthing SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:12984-1 syncthing-1.23.5-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
References
- https://github.com/syncthing/syncthing/security/advisories/GHSA-9rp6-23gf-4c3h
- https://github.com/syncthing/syncthing/commit/73c52eafb6566435dffd979c3c49562b6d5a4238
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/IRYGBFJPVBW6PPTETNIBWQJE4HJSA5PJ/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/XEBWSQVGHSTR4ZO7LVVEMPEGMV2DS5XR/