CVE-2026-62303Pistache: DoS via stack exhaustion in REST router path normalization (regex_replace on long slash runs)

Official description

Pistache is a high-performance REST toolkit written in C++. From 0.0.5 through 0.4.26, `SegmentTreeNode::sanitizeResource()` in `src/server/router.cc` uses `std::regex_replace()` with the `//+` expression to collapse consecutive slashes. With libstdc++, a path containing tens of thousands of consecutive slash characters can recurse deeply enough to exhaust the stack and crash the process. `Router::route()`, `Router::addRoute()` and `Router::removeRoute()` reach this normalization. Unauthenticated remote exploitation is conditional on a deployment allowing sufficiently long request paths, such as by increasing `Endpoint::Options::maxRequestSize()` above the default 4096-byte limit or forwarding long paths through a front end. Direct router API use is also affected when attacker-controlled route or resource strings reach the normalizer. Native builds reproduced a crash around 24,000 consecutive slashes, although the exact threshold depends on the stack and standard library; the demonstrated failure is stack exhaustion rather than uninitialized-memory use. A source fix replaces recursive regular-expression normalization with an iterative pass, but no containing repository release was verified as of time of publication.

Affected packages & fixed versions

Affected products (as reported)

References

• https://github.com/pistacheio/pistache/security/advisories/GHSA-q474-pqcp-gqm5 x_refsource_CONFIRM
• https://github.com/pistacheio/pistache/commit/935461352403696f3ca0dbb9a7de7d2609e7ce91 x_refsource_MISC