RIO DE JANEIRO — As Brazil weathers the worst political and economic crises in living memory, Brazilians can hardly be blamed for being distracted. But there is a subject that the country’s politicians — and citizens — are not discussing, even though it risks tarnishing Brazil’s international reputation as an advocate of peacebuilding and diplomacy: an unchecked arms industry and its involvement in foreign conflicts around the globe.

The fingerprints of Brazil’s largest arms companies are turning up in a growing number of the world’s hot spots, including Yemen, where thousands of civilians are perishing in a punishing war with no end in sight. An investigation last month into Forjas Taurus, the Brazilian firearms manufacturer, revealed that the company supplied weapons to a notorious Yemeni arms dealer. Two (now former) executives of the company — Latin America’s largest — have been charged with illegal arms transfers, though the case remains under seal. Taurus, which is involved in the case only as an interested party, has denied any wrongdoing and says it is working to “clarify the facts.”

The details of Taurus’s misdeeds read like a spy novel. Brazilian prosecutors allege that Fares Mohammed Hassan Mana’a, a widely known arms smuggler and former governor in Yemen, diverted a consignment of 8,000 handguns from Djibouti across the Bab el-Mandeb Strait to Yemen. Mr. Mana’a is believed to have been supporting Houthi rebels in their fight against a Saudi- and United States-backed government.

The civil war in Yemen has already killed an estimated 10,000 people since early 2015 and displaced more than three million. The United States, which has provided material and logistical support for the Saudi bombing campaign, has been under intense pressure to clarify its involvement in the civil war because of the humanitarian toll and the United States’ increasingly direct role in the conflict.