Short answer. No. Civil Code Article 925 caps your liability at the value of the legacy or devise you actually received. A legatee or devisee charged with paying someone else is liable for that charge only to the extent of what their legacy is worth, never beyond it.
What the law says
The latter shall be liable for the charge only to the extent of the value of the legacy or the devise received by them.
Civil Code, Article 925 — Who May Be Charged. Read the full provision →
A testator can charge a legatee, not just an heir
Article 925 confirms that a testator's power to attach obligations to a bequest is not limited to compulsory heirs. A testator may charge with legacies and devises not only his compulsory heirs but also the legatees and devisees. This is what makes your situation possible in the first place: the will can validly direct that the legacy left to you also carries a duty to pay something to a third person, and that arrangement is recognized as valid under this article.
The cap on your liability
The protection you are asking about is written directly into the same article. The latter shall be liable for the charge only to the extent of the value of the legacy or the devise received by them. 'The latter' refers back to the legatees and devisees just mentioned. In practice this means your exposure is capped at what you actually received: if the legacy is worth less than the amount you were charged to pay, you are not required to make up the difference out of your own separate assets. The charge rides on the legacy, and stops where the legacy's value stops.
How compulsory heirs are treated differently
The article draws the same kind of cap for compulsory heirs, though pegged to a different measure: the compulsory heirs shall not be liable for the charge beyond the amount of the free portion given them. A compulsory heir's protected legitime cannot be reached to satisfy a charge; only whatever free portion the testator additionally gave them is exposed. Both rules share the same underlying principle, that nobody named in a will to carry a testamentary charge can be made to pay more than the value of what the will actually gave them.
What determines the value of your cap
Because your liability is measured against the value of the legacy you actually received, that valuation becomes the key practical question if a dispute arises over how much you owe. If the legacy consists of property that has since changed in value, or if there is disagreement about what it was worth at the relevant time, that factual question shapes the ceiling on what you can be made to pay. What Article 925 guarantees is the principle itself, that the charge cannot exceed the legacy's value, not a fixed peso figure, since the figure depends entirely on what was actually left to you.