CVE-2026-45870 SUNRPC: auth_gss: fix memory leaks in XDR decoding error paths
A memory leak in the Linux kernel's SUNRPC auth_gss module allows attackers to exhaust system memory via crafted XDR decoding errors, causing denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-45870?
CVE-2026-45870 is a medium-severity denial of service vulnerability in Linux kernel, published on 27 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
SUNRPC: auth_gss: fix memory leaks in XDR decoding error paths
The gssx_dec_ctx(), gssx_dec_status(), and gssx_dec_name() functions allocate memory via gssx_dec_buffer(), which calls kmemdup(). When a subsequent decode operation fails, these functions return immediately without freeing previously allocated buffers, causing memory leaks.
The leak in gssx_dec_ctx() is particularly relevant because the caller (gssp_accept_sec_context_upcall) initializes several buffer length fields to non-zero values, resulting in memory allocation:
struct gssx_ctx rctxh = { .exported_context_token.len = GSSX_max_output_handle_sz, .mech.len = GSS_OID_MAX_LEN, .src_name.display_name.len = GSSX_max_princ_sz, .targ_name.display_name.len = GSSX_max_princ_sz };
If, for example, gssx_dec_name() succeeds for src_name but fails for targ_name, the memory allocated for exported_context_token, mech, and src_name.display_name remains unreferenced and cannot be reclaimed.
Add error handling with goto-based cleanup to free any previously allocated buffers before returning an error.
Weakness: CWE-401
Which versions are affected by CVE-2026-45870?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-45870?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-45870 being exploited?
There is no known exploitation of CVE-2026-45870 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-45870, DEBIAN-CVE-2026-45870, GHSA-cc2x-2xg8-9rpf, ROOT-OS-UBUNTU-2204-CVE-2026-45870, ROOT-OS-UBUNTU-2404-CVE-2026-45870, UBUNTU-CVE-2026-45870.