Description
An issue was discovered in the function mark_beginning_as_normal in nfa.c in flex 2.6.4. There is a stack exhaustion problem caused by the mark_beginning_as_normal function making recursive calls to itself in certain scenarios involving lots of '*' characters. Remote attackers could leverage this vulnerability to cause a denial-of-service.
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 | flex | No fix yet | — |
| Debian 13 | flex | No fix yet | — |
| Debian 12 | flex | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | flex | No fix yet | — |
| Ubuntu 26.04 LTS | flex | No fix yet | — |
| Ubuntu 25.10 | flex | No fix yet | — |
| Ubuntu 24.04 LTS | flex | No fix yet | — |
| Ubuntu 22.04 LTS | flex | No fix yet | — |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | flex | No fix yet | — |
| Ubuntu 18.04 LTS | flex | No fix yet | — |
| Ubuntu 16.04 LTS | flex | No fix yet | — |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | flex | 2.6.4-7 | — |
| Azure Linux 2 (CBL-Mariner) | flex | 2.6.4-7 | — |