tracing: Reject incomplete event filter expressions
- Exploited
- No known exploitation
- Fix
- No fix listed
- Who is exposed
- Specific setups only
Do first: Check whether your setup matches what the bug needs. The filter input ends after a logical operator, possibly followed by unary '!' tokens. A self-targeted perf tracepoint counting event can reach the affected path through PERF_EVENT_IOC_SET_FILTER.
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- Published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 38/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
In the Linux kernel, the following vulnerability has been resolved: tracing: Reject incomplete event filter expressions A non-empty expression normally finishes in predicate_parse()'s inner loop, which resolves the pending logical operators before jumping to finalization. If the input ends after an operator, possibly followed by unary '!' tokens, the outer loop instead falls through with unresolved operator state. For example, "common_pid == 1 || common_pid == 2 &&" leaves prog[0].target equal to -1. The second pass then reads prog[-1] before the forward-jump check can reject it. Depending on adjacent slab contents, it can also copy an out-of-bounds word into a branch target that passes the forward-only check. A self-targeted perf tracepoint counting event can reach this path through PERF_EVENT_IOC_SET_FILTER. Reject the outer-loop fallthrough when a predicate has already been parsed. This ensures that non-empty expressions only reach finalization after the inner loop has resolved their operators. Keep the existing no-filter error for input that has no predicates. Add a regression test for trailing logical operators and unary negations.
What to do
Check whether your setup matches what the bug needs.
The filter input ends after a logical operator, possibly followed by unary '!' tokens. A self-targeted perf tracepoint counting event can reach the affected path through PERF_EVENT_IOC_SET_FILTER.Workaround: The facts give no official workaround. The only trigger path they describe is setting a filter on a self-targeted perf tracepoint counting event, so avoiding that use is the only limiting step the facts support, though it is not a documented fix.
Timeline
- CVE published
- First seen by cve.now
- Posted on X by cve.now
Affected versions
- Linux Linux
Version range not reported
- Linux Linux
4.17
Evidence 8
- Link
- Link
- Link
- Link
- Link
Corrections
None so far.
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Questions about CVE-2026-99236
What does this mean?
The kernel's tracing event filter parser accepts filter input that ends after a logical operator, possibly followed by unary '!' tokens. The second parsing pass then reads memory before the start of the program array (prog[-1]), which is an out-of-bounds kernel memory read. The advisory also says an out-of-bounds word may be copied into a branch target.Source: git.kernel.org
Am I affected, and how do I check?
The affected product is listed as the Linux kernel, but the facts give no version ranges. The reported path needs a self-targeted perf tracepoint counting event that receives a filter through PERF_EVENT_IOC_SET_FILTER. To check a system, compare its kernel version (uname -r) with the version ranges in the official advisory.Source: git.kernel.org
What should I do about it?
The facts do not name a fixed kernel version, so no upgrade target can be given from them. Check the official advisory or the upstream kernel stable updates for a patched release, and install the vendor's kernel update once it is available.Source: git.kernel.org
Is it being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What if there's no patch?
The facts give no official workaround. The only trigger path they describe is setting a filter on a self-targeted perf tracepoint counting event, so avoiding that use is the only limiting step the facts support, though it is not a documented fix.Source: git.kernel.org