CVE-2025-39836
CVE-2025-39836 is a high-severity vulnerability in Linux Linux Kernel with a CVSS 3.x base score of 7.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-787.
Key facts
- Severity: High (CVSS 3.x base score 7.8)
- EPSS exploit prediction: 0% (4th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2025-29578
- Weakness: CWE-787
- Affected product: Linux Linux Kernel
- Published:
- Last modified:
Description
In the Linux kernel, the following vulnerability has been resolved: efi: stmm: Fix incorrect buffer allocation method The communication buffer allocated by setup_mm_hdr() is later on passed to tee_shm_register_kernel_buf(). The latter expects those buffers to be contiguous pages, but setup_mm_hdr() just uses kmalloc(). That can cause various corruptions or BUGs, specifically since commit 9aec2fb0fd5e ("slab: allocate frozen pages"), though it was broken before as well. Fix this by using alloc_pages_exact() instead of kmalloc().
Frequently asked questions
- What is CVE-2025-39836?
- In the Linux kernel, the following vulnerability has been resolved: efi: stmm: Fix incorrect buffer allocation method The communication buffer allocated by setup_mm_hdr() is later on passed to tee_shm_register_kernel_buf(). The latter expects those buffers to be contiguous pages, but setup_mm_hdr() just uses kmalloc(). That can cause various corruptions or BUGs, specifically since commit 9aec2fb0fd5e ("slab: allocate frozen pages"), though it was broken before as well. Fix this by using alloc_pages_exact() instead of kmalloc().
- How severe is CVE-2025-39836?
- CVE-2025-39836 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
- Is CVE-2025-39836 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (4th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2025-39836?
- CVE-2025-39836 primarily affects Linux Linux Kernel. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
- How do I fix CVE-2025-39836?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- Does CVE-2025-39836 have an EU (EUVD) identifier?
- Yes. CVE-2025-39836 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-29578.
- When was CVE-2025-39836 published?
- CVE-2025-39836 was published on 2025-09-16 and last updated on 2026-06-17.
References
- https://git.kernel.org/stable/c/630c0e6064daf84f17aad1a7d9ca76b562e3fe47
- https://git.kernel.org/stable/c/77ff27ff0e4529a003c8a1c2492c111968c378d3
- https://git.kernel.org/stable/c/c5e81e672699e0c5557b2b755cc8f7a69aa92bff
Affected products (4)
- cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
- cpe:2.3:o:linux:linux_kernel:6.17:rc1:*:*:*:*:*:*
- cpe:2.3:o:linux:linux_kernel:6.17:rc2:*:*:*:*:*:*
- cpe:2.3:o:linux:linux_kernel:6.17:rc3:*:*:*:*:*:*
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