CVE-2020-27618 is a medium-severity vulnerability found in the iconv function of the GNU C Library (glibc), versions 2.32 and earlier. The vulnerability arises when iconv processes invalid multi-byte input sequences specifically in the IBM1364, IBM1371, IBM1388, IBM1390, and IBM1399 character encodings. In these cases, the function fails to advance the input state correctly, causing the application to enter an infinite loop. This infinite loop results in a denial of service (DoS) condition, where the affected application becomes unresponsive or consumes excessive CPU resources. This vulnerability is distinct from a previously known issue (CVE-2016-10228) but shares the same root cause related to improper handling of invalid multi-byte sequences. The vulnerability requires local access with low privileges (AV:L, PR:L) and does not require user interaction (UI:N). It impacts availability but does not affect confidentiality or integrity. The vulnerability is classified under CWE-835 (Loop with Unreachable Exit Condition), indicating a logic flaw that prevents normal termination of a loop. No known public exploits have been reported, and no official patches are linked in the provided data, although it is expected that glibc maintainers would address this in subsequent releases. The vulnerability affects applications that rely on glibc's iconv function for character encoding conversions involving the specified IBM code pages, which are less common but may be used in legacy systems or specialized environments.

For European organizations, the primary impact of CVE-2020-27618 is the potential for denial of service conditions in applications that utilize glibc's iconv function to process IBM1364, IBM1371, IBM1388, IBM1390, or IBM1399 encoded data. This could affect legacy systems, middleware, or specialized software handling these encodings, potentially leading to service outages or degraded performance. While the vulnerability does not compromise data confidentiality or integrity, the availability impact could disrupt business operations, especially in sectors relying on continuous uptime such as finance, telecommunications, and critical infrastructure. European organizations with legacy IBM mainframe integration or those using software that processes these specific encodings are at higher risk. The lack of known exploits reduces immediate threat levels, but the vulnerability could be leveraged in targeted attacks or accidental triggers causing system instability. Given the medium severity and local access requirement, the risk is moderate but should not be ignored in environments where affected encodings are processed.

To mitigate CVE-2020-27618, European organizations should: 1) Identify and inventory systems using glibc versions 2.32 or earlier, particularly those processing IBM1364, IBM1371, IBM1388, IBM1390, or IBM1399 encoded data. 2) Upgrade glibc to the latest stable version where this vulnerability is patched. If an official patch is not yet available, consider applying vendor-provided workarounds or backported fixes. 3) Implement input validation and sanitization to detect and reject invalid multi-byte sequences before they reach the iconv function, reducing the risk of triggering the infinite loop. 4) Monitor application logs and system performance for signs of infinite loops or high CPU usage that could indicate exploitation attempts or accidental triggers. 5) Restrict local access to critical systems to trusted personnel only, minimizing the risk of exploitation given the local access requirement. 6) For legacy applications that cannot be updated promptly, consider isolating them in controlled environments or using containerization to limit impact. 7) Engage with software vendors and maintain awareness of updates related to glibc and dependent applications.