CVE-2026-123042
Description
A double-free and use-after-free vulnerability was found in NFS-Ganesha. When an NFSv4.1 COMPOUND request caches a READ reply in the session-slot replay cache, the READ data buffer is freed on first transmission but the cache retains a dangling pointer. A subsequent legal protocol replay re-sends the freed buffer contents to the client and frees the pointer again, resulting in remote heap information disclosure and a daemon crash.
Statement
Red Hat Ceph Storage 4 ships nfs-ganesha 3.5, which predates the introduction of the zero-copy iovec READ path in V6.0 (commit 48e5220b2) and is therefore not affected by this vulnerability.
Red Hat Ceph Storage 9 ships nfs-ganesha versions V7.0 and later inside the rhceph container images, which include the vulnerable code path. The NFSv4.1 session-slot replay cache stores READ reply buffers by shallow pointer, allowing a legal protocol replay to re-encode freed heap memory and free the same buffer again. Exploitation requires only TCP reachability to the NFS port; on AUTH_SYS or AUTH_NONE exports no real credential is needed.
Mitigation
Restricting NFS exports to Kerberos-only authentication (SecType = krb5/krb5i/krb5p) prevents unauthenticated exploitation, though authenticated clients can still trigger the bug. Network segmentation to restrict NFS port access reduces the attack surface.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8.1 | N/A | N/A |
| Attack Vector | Network | N/A | N/A |
| Attack Complexity | Low | N/A | N/A |
| Privileges Required | Low | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | High | N/A | N/A |
| Integrity Impact | None | N/A | N/A |
| Availability Impact | High | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Red Hat CVSS v3 Score Explanation
PR:L: AUTH_SYS is an asserted identity (low privilege). C:H: attacker-controlled heap chunk size disclosed via UAF read. A:H: deterministic crash via double-free, unbounded replay.
Understanding the Weakness (CWE)
Integrity,Confidentiality,Availability
Technical Impact: Modify Memory; Execute Unauthorized Code or Commands
When a program calls free() twice with the same argument, the program's memory management data structures may become corrupted, potentially leading to the reading or modification of unexpected memory addresses. This corruption can cause the program to crash or, in some circumstances, cause two later calls to malloc() to return the same pointer. If malloc() returns the same value twice and the program later gives the attacker control over the data that is written into this doubly-allocated memory, the program becomes vulnerable to a buffer overflow attack. Doubly freeing memory may result in a write-what-where condition, allowing an attacker to execute arbitrary code.
Acknowledgements
Red Hat would like to thank Jiwoong Wi (Tobabz Team) for reporting this issue.
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