CVE-2026-89606

A flaw was found in ecryptfs, a component of the Linux kernel. This vulnerability allows a remote attacker to send a specially crafted tag 70 packet with a body smaller than expected. This can lead to an integer underflow during size calculation, potentially causing a denial of service (DoS) or system instability.

A moderate-severity flaw was found in the eCryptFS implementation of the Linux kernel. When parsing a tag 70 packet, ecryptfs_parse_tag_70_packet() subtracts fixed metadata fields from the packet body size to derive the encrypted filename size; a malformed packet with a body smaller than those fixed fields can underflow this size calculation, potentially causing a kernel panic and resulting in a local denial of service or system instability. Exploitation requires local access to a system using eCryptFS and the ability to supply a specially crafted tag 70 packet, and Red Hat assesses the attack complexity as high; this is why the Red Hat CVSS v3.1 score of 7.0 is lower than the upstream score of 7.8, which assumes low attack complexity.

Red Hat Enterprise Linux kernel streams (RHEL 7, 8, 9, and 10) have been assessed as not affected because the vulnerable code is not present in those builds. The Red Hat Enterprise Linux CoreOS (RHCOS) components shipped with OpenShift Container Platform 5.0 and 5.1 are affected, and fixes for these streams are currently deferred. Given the flaw's moderate impact and the local, high-complexity attack path, the residual risk until a fix is delivered is primarily a local denial of service on affected hosts where eCryptFS is in use.

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.