Summary
In the Linux kernel, the following vulnerability has been resolved: mm: fix uprobe pte be...
In the Linux kernel, the following vulnerability has been resolved:
mm: fix uprobe pte be overwritten when expanding vma
Patch series "Fix uprobe pte be overwritten when expanding vma".
This patch (of 4):
We encountered a BUG alert triggered by Syzkaller as follows:
BUG: Bad rss-counter state mm:00000000b4a60fca type:MM_ANONPAGES val:1
And we can reproduce it with the following steps:
- register uprobe on file at zero offset
- mmap the file at zero offset:
addr1 = mmap(NULL, 2 * 4096, PROT_NONE, MAP_PRIVATE, fd, 0); - mremap part of vma1 to new vma2:
addr2 = mremap(addr1, 4096, 2 * 4096, MREMAP_MAYMOVE); - mremap back to orig addr1:
mremap(addr2, 4096, 4096, MREMAP_MAYMOVE | MREMAP_FIXED, addr1);
In step 3, the vma1 range [addr1, addr1 + 4096] will be remap to new vma2
with range [addr2, addr2 + 8192], and remap uprobe anon page from the vma1
to vma2, then unmap the vma1 range [addr1, addr1 + 4096].
In step 4, the vma2 range [addr2, addr2 + 4096] will be remap back to the
addr range [addr1, addr1 + 4096]. Since the addr range [addr1 + 4096,
addr1 + 8192] still maps the file, it will take vma_merge_new_range to
expand the range, and then do uprobe_mmap in vma_complete. Since the
merged vma pgoff is also zero offset, it will install uprobe anon page to
the merged vma. However, the upcomming move_page_tables step, which use
set_pte_at to remap the vma2 uprobe pte to the merged vma, will overwrite
the newly uprobe pte in the merged vma, and lead that pte to be orphan.
Since the uprobe pte will be remapped to the merged vma, we can remove the
unnecessary uprobe_mmap upon merged vma.
This problem was first found in linux-6.6.y and also exists in the
community syzkaller:
https://lore.kernel.org/all/[email protected]/T/
Impact
CVE-2025-38207 has a CVSS score of 5.5 (Medium). The vector is requires local access, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. No fixed version is listed yet, so configuration controls and monitoring matter more in the interim.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2025-38207? CVE-2025-38207 is a medium-severity security vulnerability. No fixed version is listed yet.
- How severe is CVE-2025-38207? CVE-2025-38207 has a CVSS score of 5.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Is there a fix for CVE-2025-38207? No fixed version is listed for CVE-2025-38207 yet. Monitor the advisory for updates and apply mitigations in the interim.
- Is CVE-2025-38207 exploitable, and should I be worried? Whether CVE-2025-38207 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2025-38207 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.