CVE-2026-63209

A flaw was found in the klauspost/compress package. A remote attacker can exploit this vulnerability by supplying a specially crafted compression dictionary with an excessively large repeat value, triggering an integer overflow. When the dictionary is subsequently processed, this overflow leads to out-of-bounds memory access, crashing the application and resulting in a Denial of Service (DoS).

Red Hat has rated this vulnerability as having an impact of Important because an unauthenticated remote attacker could trigger a denial of service by causing a process crash without requiring elevated permissions. In Red Hat environments where this Go library is embedded, exploitation requires that an application accepts untrusted dictionary structures for S2 compression and subsequently attempts encoding. Although the resulting memory access fault terminates the vulnerable process, the flaw is confined to process crashes and does not compromise data confidentiality or integrity.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.