[ Reason ]
CVE-2026-107161 heap-based buffer overflow fix.

[ Impact ]
Crash of the application (denial of service).

[ Tests ]
I have introduced a regression test in autokpgtest that checks the
library for exploitability.

[ Risks ]
One line change with recalculation of one variable.
Usual library users are not affected by any behavior change.

[ Checklist ]
  [x] *all* changes are documented in the d/changelog
  [x] I reviewed all changes and I approve them
  [x] attach debdiff against the package in stable
  [x] the issue is verified as fixed in unstable

[ Changes ]
The fix comes from the CVE-2026-107161 report.

Please find a debdiff version attached with corrected target distribution.
Somehow even though I have used dch --stable, trixie-security was
auto-generated...