CVE-2026-98969 (GCVE-0-2026-98969)
Vulnerability from cvelistv5
Published
2026-10-23 12:19
Modified
2026-10-30 12:40
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
net/sched: em_text: reject unterminated algo before autoload
This is a follow-up to commit 9c572a83037a ("net/sched: fix potential
stack infoleak in em_text_dump()"), which zero-initialised the dump-side
struct. Sashiko pointed at a pre-existing bug that exposed the change-side
input-validation gap open.
em_text_change() casts the raw netlink attribute payload to struct
tcf_em_text and passes conf->algo, a 16-byte array with no enforced NUL
terminator, to textsearch_prepare(). On the TS_AUTOLOAD retry
textsearch_prepare() calls request_module("ts_%s", algo); vsnprintf()
walks %s until it finds a NUL, so an algo[] with no NUL reads past the
array into the adjacent struct fields and payload and feeds those bytes
to the usermode helper command line. This is an out-of-bounds read and
a kernel memory disclosure.
Reject the attribute when no NUL exists within TC_EM_TEXT_ALGOSIZ bytes,
matching the check xt_string has had since 3ab720881b6e.
Conditions to recreate the bug:
- CAP_NET_ADMIN on the target netns (namespace-local via unshare -Urn
is enough)
- install clsact on an interface, then add a basic filter with one text
ematch whose algo[] is 16 bytes with no NUL (e.g. "A"*16) and
pattern_len at least 1
- the add fails with -ENOENT and the kernel invokes modprobe with a
module name made of "ts_" plus the 16 bytes and the adjacent payload
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: d675c989ed2d4ba23dff615330b04371aea83534 Version: d675c989ed2d4ba23dff615330b04371aea83534 Version: d675c989ed2d4ba23dff615330b04371aea83534 Version: d675c989ed2d4ba23dff615330b04371aea83534 Version: d675c989ed2d4ba23dff615330b04371aea83534 Version: d675c989ed2d4ba23dff615330b04371aea83534 Version: d675c989ed2d4ba23dff615330b04371aea83534 Version: d675c989ed2d4ba23dff615330b04371aea83534 |
||
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"descriptions": [
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"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: em_text: reject unterminated algo before autoload\n\nThis is a follow-up to commit 9c572a83037a (\"net/sched: fix potential\nstack infoleak in em_text_dump()\"), which zero-initialised the dump-side\nstruct. Sashiko pointed at a pre-existing bug that exposed the change-side\ninput-validation gap open.\n\nem_text_change() casts the raw netlink attribute payload to struct\ntcf_em_text and passes conf-\u003ealgo, a 16-byte array with no enforced NUL\nterminator, to textsearch_prepare(). On the TS_AUTOLOAD retry\ntextsearch_prepare() calls request_module(\"ts_%s\", algo); vsnprintf()\nwalks %s until it finds a NUL, so an algo[] with no NUL reads past the\narray into the adjacent struct fields and payload and feeds those bytes\nto the usermode helper command line. This is an out-of-bounds read and\na kernel memory disclosure.\n\nReject the attribute when no NUL exists within TC_EM_TEXT_ALGOSIZ bytes,\nmatching the check xt_string has had since 3ab720881b6e.\n\nConditions to recreate the bug:\n- CAP_NET_ADMIN on the target netns (namespace-local via unshare -Urn\n is enough)\n- install clsact on an interface, then add a basic filter with one text\n ematch whose algo[] is 16 bytes with no NUL (e.g. \"A\"*16) and\n pattern_len at least 1\n- the add fails with -ENOENT and the kernel invokes modprobe with a\n module name made of \"ts_\" plus the 16 bytes and the adjacent payload"
}
],
"providerMetadata": {
"dateUpdated": "2026-10-30T12:40:35.763Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"url": "https://git.kernel.org/stable/c/64153f1dd14dabfd4e79bf506bb5b5d66f7b42eb"
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{
"url": "https://git.kernel.org/stable/c/b62fb105961b677418cbc0a0a8837a41735729ec"
},
{
"url": "https://git.kernel.org/stable/c/b4da5c85cd701066ff429727fb61b84bde8bcce2"
},
{
"url": "https://git.kernel.org/stable/c/00bcc303000bac524d62eed054d77372b38ace0f"
},
{
"url": "https://git.kernel.org/stable/c/22182f91c6703af6e9832cffe6d22b381031cb5a"
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{
"url": "https://git.kernel.org/stable/c/85e5512369d4fe6e5f2c43712d9f9e01d4ae8437"
},
{
"url": "https://git.kernel.org/stable/c/b627c6ba20be20334338229b4820baacb9d96826"
},
{
"url": "https://git.kernel.org/stable/c/c9728fcf2e7fb4a7a8d08ebd9524c3b02ae1a021"
}
],
"title": "net/sched: em_text: reject unterminated algo before autoload",
"x_generator": {
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"cveId": "CVE-2026-98969",
"datePublished": "2026-10-23T12:19:42.012Z",
"dateReserved": "2026-09-25T10:25:14.383Z",
"dateUpdated": "2026-10-30T12:40:35.763Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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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.
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