Description
libjwt 1.15.3 uses strcmp (which is not constant time) to verify authentication, which makes it easier to bypass authentication via a timing side channel.
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 | libjwt | 1.17.0-2 | — |
| Debian 13 | libjwt | 1.17.0-2 | — |
| Debian 12 | libjwt | 1.10.2-1+deb12u1 | — |
| Debian 10 | libjwt | 1.10.1-1+deb10u1 | DLA-3739-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 25.10 | libjwt | No fix yet | — |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 22.04 LTS | libjwt | 1.10.2-1ubuntu0.22.04.1~esm1 | USN-9075-1 |
| Ubuntu Pro 20.04 LTS | libjwt | 1.10.2-1ubuntu0.20.04.1~esm1 | USN-9075-1 |
| Ubuntu Pro 18.04 LTS | libjwt | 1.9.0-1ubuntu0.1~esm1 | USN-9075-1 |
Advisories 2
- USN-9075-1 libjwt vulnerability Ubuntu Security Notices (USN) · Nov 13, 2026
- DLA-3739-1 libjwt - security update Debian Security (DSA / DLA) · Mar 9, 2026