In the Linux kernel, the following vulnerability has been resolved:
net: atm: fix crash due to unvalidated vcc pointer in sigd_send()
Reproducer available at [1].
The ATM send path (sendmsg -> vcc_sendmsg -> sigd_send) reads the vcc
pointer from msg->vcc and uses it directly without any validation. This
pointer comes from userspace via sendmsg() and can be arbitrarily forged:
int fd = socket(AF_ATMSVC, SOCK_DGRAM, 0);
ioctl(fd, ATMSIGD_CTRL); // become ATM signaling daemon
struct msghdr msg = { .msg_iov = &iov, ... };
*(unsigned long *)(buf + 4) = 0xdeadbeef; // fake vcc pointer
sendmsg(fd, &msg, 0); // kernel dereferences 0xdeadbeef
In normal operation, the kernel sends the vcc pointer to the signaling
daemon via sigd_enq() when processing operations like connect(), bind(),
or listen(). The daemon is expected to return the same pointer when
responding. However, a malicious daemon can send arbitrary pointer values.
Fix this by introducing find_get_vcc() which validates the pointer by
searching through vcc_hash (similar to how sigd_close() iterates over
all VCCs), and acquires a reference via sock_hold() if found.
Since struct atm_vcc embeds struct sock as its first member, they share
the same lifetime. Therefore using sock_hold/sock_put is sufficient to
keep the vcc alive while it is being used.
Note that there may be a race with sigd_close() which could mark the vcc
with various flags (e.g., ATM_VF_RELEASED) after find_get_vcc() returns.
However, sock_hold() guarantees the memory remains valid, so this race
only affects the logical state, not memory safety.
[1]: https://gist.github.com/mrpre/1ba5949c45529c511152e2f4c755b0f3
References
Configurations
Configuration 1 (hide)
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History
20 May 2026, 16:03
| Type | Values Removed | Values Added |
|---|---|---|
| CPE | cpe:2.3:o:linux:linux_kernel:2.6.12:rc3:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:2.6.12:rc5:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:2.6.12:rc4:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:2.6.12:rc2:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc7:*:*:*:*:*:* |
|
| References | () https://git.kernel.org/stable/c/1c8bda3df028d5e54134077dcd09f46ca8cfceb5 - Patch | |
| References | () https://git.kernel.org/stable/c/21c303fec138c002f90ed33bce60e807d53072bb - Patch | |
| References | () https://git.kernel.org/stable/c/3e1a8b00095246a9a2b46b57f6d471c6d3c00ed2 - Patch | |
| References | () https://git.kernel.org/stable/c/440c9a5fc477a8ee259d8bf669531250b8398651 - Patch | |
| References | () https://git.kernel.org/stable/c/69d3f9ee5489e6e8b66defcfa226e91d82393297 - Patch | |
| References | () https://git.kernel.org/stable/c/ae88a5d2f29b69819dc7b04086734439d074a643 - Patch | |
| References | () https://git.kernel.org/stable/c/c96549d07dfdd51aadf0722cfb40711574424840 - Patch | |
| References | () https://git.kernel.org/stable/c/e3f80666c2739296c3b69a127300455c43aa1067 - Patch | |
| First Time |
Linux linux Kernel
Linux |
|
| CWE | CWE-476 | |
| CVSS |
v2 : v3 : |
v2 : unknown
v3 : 5.5 |
08 Apr 2026, 14:16
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Information
Published : 2026-04-08 14:16
Updated : 2026-05-20 16:03
NVD link : CVE-2026-31411
Mitre link : CVE-2026-31411
CVE.ORG link : CVE-2026-31411
JSON object : View
Products Affected
linux
- linux_kernel
CWE
CWE-476
NULL Pointer Dereference