CVE-2026-31411 (GCVE-0-2026-31411)
Vulnerability from cvelistv5
Published
2026-04-08 13:06
Modified
2026-04-13 06:08
Severity ?
VLAI Severity ?
EPSS score ?
Summary
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
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 |
||
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/atm/signaling.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "c96549d07dfdd51aadf0722cfb40711574424840",
"status": "affected",
"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
"versionType": "git"
},
{
"lessThan": "1c8bda3df028d5e54134077dcd09f46ca8cfceb5",
"status": "affected",
"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
"versionType": "git"
},
{
"lessThan": "3e1a8b00095246a9a2b46b57f6d471c6d3c00ed2",
"status": "affected",
"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
"versionType": "git"
},
{
"lessThan": "e3f80666c2739296c3b69a127300455c43aa1067",
"status": "affected",
"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
"versionType": "git"
},
{
"lessThan": "21c303fec138c002f90ed33bce60e807d53072bb",
"status": "affected",
"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
"versionType": "git"
},
{
"lessThan": "69d3f9ee5489e6e8b66defcfa226e91d82393297",
"status": "affected",
"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
"versionType": "git"
},
{
"lessThan": "440c9a5fc477a8ee259d8bf669531250b8398651",
"status": "affected",
"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
"versionType": "git"
},
{
"lessThan": "ae88a5d2f29b69819dc7b04086734439d074a643",
"status": "affected",
"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"net/atm/signaling.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "2.6.12"
},
{
"lessThan": "2.6.12",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.252",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.202",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.165",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.128",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.75",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.14",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.19.*",
"status": "unaffected",
"version": "6.19.4",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.0",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.10.252",
"versionStartIncluding": "2.6.12",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.15.202",
"versionStartIncluding": "2.6.12",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.1.165",
"versionStartIncluding": "2.6.12",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.6.128",
"versionStartIncluding": "2.6.12",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.75",
"versionStartIncluding": "2.6.12",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.14",
"versionStartIncluding": "2.6.12",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.19.4",
"versionStartIncluding": "2.6.12",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.0",
"versionStartIncluding": "2.6.12",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: atm: fix crash due to unvalidated vcc pointer in sigd_send()\n\nReproducer available at [1].\n\nThe ATM send path (sendmsg -\u003e vcc_sendmsg -\u003e sigd_send) reads the vcc\npointer from msg-\u003evcc and uses it directly without any validation. This\npointer comes from userspace via sendmsg() and can be arbitrarily forged:\n\n int fd = socket(AF_ATMSVC, SOCK_DGRAM, 0);\n ioctl(fd, ATMSIGD_CTRL); // become ATM signaling daemon\n struct msghdr msg = { .msg_iov = \u0026iov, ... };\n *(unsigned long *)(buf + 4) = 0xdeadbeef; // fake vcc pointer\n sendmsg(fd, \u0026msg, 0); // kernel dereferences 0xdeadbeef\n\nIn normal operation, the kernel sends the vcc pointer to the signaling\ndaemon via sigd_enq() when processing operations like connect(), bind(),\nor listen(). The daemon is expected to return the same pointer when\nresponding. However, a malicious daemon can send arbitrary pointer values.\n\nFix this by introducing find_get_vcc() which validates the pointer by\nsearching through vcc_hash (similar to how sigd_close() iterates over\nall VCCs), and acquires a reference via sock_hold() if found.\n\nSince struct atm_vcc embeds struct sock as its first member, they share\nthe same lifetime. Therefore using sock_hold/sock_put is sufficient to\nkeep the vcc alive while it is being used.\n\nNote that there may be a race with sigd_close() which could mark the vcc\nwith various flags (e.g., ATM_VF_RELEASED) after find_get_vcc() returns.\nHowever, sock_hold() guarantees the memory remains valid, so this race\nonly affects the logical state, not memory safety.\n\n[1]: https://gist.github.com/mrpre/1ba5949c45529c511152e2f4c755b0f3"
}
],
"providerMetadata": {
"dateUpdated": "2026-04-13T06:08:40.030Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/c96549d07dfdd51aadf0722cfb40711574424840"
},
{
"url": "https://git.kernel.org/stable/c/1c8bda3df028d5e54134077dcd09f46ca8cfceb5"
},
{
"url": "https://git.kernel.org/stable/c/3e1a8b00095246a9a2b46b57f6d471c6d3c00ed2"
},
{
"url": "https://git.kernel.org/stable/c/e3f80666c2739296c3b69a127300455c43aa1067"
},
{
"url": "https://git.kernel.org/stable/c/21c303fec138c002f90ed33bce60e807d53072bb"
},
{
"url": "https://git.kernel.org/stable/c/69d3f9ee5489e6e8b66defcfa226e91d82393297"
},
{
"url": "https://git.kernel.org/stable/c/440c9a5fc477a8ee259d8bf669531250b8398651"
},
{
"url": "https://git.kernel.org/stable/c/ae88a5d2f29b69819dc7b04086734439d074a643"
}
],
"title": "net: atm: fix crash due to unvalidated vcc pointer in sigd_send()",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-31411",
"datePublished": "2026-04-08T13:06:17.800Z",
"dateReserved": "2026-03-09T15:48:24.087Z",
"dateUpdated": "2026-04-13T06:08:40.030Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
Loading…
Loading…
Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
Loading…
Loading…