CVE-2026-25727 is a stack-based buffer overflow vulnerability classified under CWE-121 affecting the Rust 'time' crate, versions from 0.3.6 up to but not including 0.3.47. The vulnerability arises during parsing of user-supplied input formatted according to the RFC 2822 date/time standard. Specifically, the flaw exploits deprecated and rarely-used features of RFC 2822 that cause excessive recursion leading to stack exhaustion, effectively resulting in a denial of service (DoS). The vulnerability does not affect normal, well-formed inputs, limiting its exposure to crafted malicious inputs. The attack complexity is high due to the need to craft inputs that trigger deep recursion, and it requires user interaction and low privileges, with no authentication needed. The vulnerability was addressed in version 0.3.47 by implementing a recursion depth limit that causes the parser to return an error instead of exhausting the stack. The CVSS 4.0 base score is 6.8, reflecting medium severity, with network attack vector, high attack complexity, no privileges required, and user interaction necessary. No known exploits have been reported in the wild as of the publication date. This vulnerability primarily impacts applications and services that rely on the 'time' crate for date/time parsing, particularly those that accept or process RFC 2822 formatted inputs, such as email clients, servers, or other communication tools written in Rust.

For European organizations, the primary impact of this vulnerability is the potential for denial of service attacks that could disrupt services relying on the Rust 'time' crate for parsing RFC 2822 date/time inputs. This could affect email processing systems, logging services, or any application that parses such date formats. The denial of service could lead to temporary outages, degraded service availability, or resource exhaustion, impacting business continuity and potentially causing reputational damage. Since the vulnerability requires user interaction and crafted inputs, exposure is somewhat limited but still significant for internet-facing services or those processing untrusted inputs. Organizations in sectors with high reliance on Rust-based software, such as technology firms, financial services, and critical infrastructure providers, may face increased risk. The medium severity score indicates that while the vulnerability is not trivial to exploit, successful exploitation could have meaningful operational impacts.

To mitigate this vulnerability, European organizations should immediately upgrade the 'time' crate to version 0.3.47 or later, where the recursion depth limit has been implemented to prevent stack exhaustion. Additionally, organizations should audit their codebases and dependencies to identify any usage of the affected versions of the 'time' crate, especially in components that parse RFC 2822 date/time inputs. Input validation and sanitization should be enhanced to detect and reject malformed or suspicious date strings that could trigger the vulnerability. Implementing runtime monitoring to detect abnormal stack usage or application crashes related to date parsing can provide early warning signs of exploitation attempts. For critical systems, consider applying application-layer firewalls or input filtering to block malformed inputs before they reach vulnerable components. Finally, maintain awareness of updates from the Rust community and CVE databases for any emerging exploits or patches.