The greenback surged nearly 1.1% to 26,050 at unofficial exchange points. At lender Vietcombank, the currency hovered at a 1.5-year low of VND25,990.
The State Bank of Vietnam lowered its reference rate by 0.02% to VND25,631.
Globally, the dollar and other major currencies were in a holding pattern on Monday as investors turned their attention to this week's US midterm elections, which could shift the balance of power in Congress and control over the federal purse strings, Reuters reported.
Ahead of the week's events, the euro was nursing losses and remained not far from a 17-month low at $1.1182 in Asian trade, weighed down by Fitch's revision of France's outlook to "negative" from "stable" after Friday's close.
Sterling was little changed at $1.3394, while the dollar eased 0.15% to 101.83 against a basket of currencies.
In other currencies, the yen fell 0.1% to 157.73 per dollar. The Australian dollar eased 0.15% to $0.7022 while the New Zealand dollar fell 0.26% to $0.5616.