CVE-2026-72043LoongArch: Fix missing dirty page tracking in {pte,pmd}_wrprotect()
- 7.1HighCVSS base score
- 0.17%Exploitation in 30 daysEPSS · top 93% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
In the Linux kernel, the following vulnerability has been resolved: LoongArch: Fix missing dirty page tracking in {pte,pmd}_wrprotect() When hardware page table walker (PTW) is enabled on LoongArch, the CPU may set _PAGE_DIRTY directly in the page table entry during a write TLB miss, without going through the software TLB store handler. The software TLB store handler (tlbex.S:254) sets both _PAGE_DIRTY and_PAGE_MODIFIED together: ori t0, t0, (_PAGE_VALID | _PAGE_DIRTY | _PAGE_MODIFIED) Since hardware PTW only sets _PAGE_DIRTY, the software-only bit, i.e. _PAGE_MODIFIED is left unchanged. This creates a window where a PTE has _PAGE_DIRTY set (hardware knows the page is dirty) but _PAGE_MODIFIED clear (software is unaware). When fork()/clone() triggers copy-on-write, __copy_present_ptes() calls pte_wrprotect(), which unconditionally clears both the _PAGE_WRITE and _PAGE_DIRTY bits: pte_val(pte) &= ~(_PAGE_WRITE | _PAGE_DIRTY); Since _PAGE_MODIFIED was never set, the dirtiness information is lost completely. Subsequently, when memory pressure triggers page reclaim, page_mkclean() / try_to_unmap() sees the page as clean (i.e. pte_dirty() returns false) and the page may be freed without writeback, causing data corruption. Fix this by propagating the _PAGE_DIRTY bit to the _PAGE_MODIFIED bit in both pte_wrprotect() and pmd_wrprotect() before clearing writeable bits: if (pte_val(pte) & _PAGE_DIRTY) pte_val(pte) |= _PAGE_MODIFIED; The pmd_wrprotect() fix handles the CONFIG_TRANSPARENT_HUGEPAGE case, where pmd entries need the same treatment. This ensures the software dirty tracking bit (checked by pte_dirty() and pmd_dirty(), which read both the _PAGE_DIRTY and _PAGE_MODIFIED bits) is preserved across fork COW write-protection. The issue was found by the LTP madvise09 test case, which exercises page reclaim after "madvise(MADV_FREE), write and fork" operation sequence on private anonymous mappings.
Timeline
ID reserved
By Linux
- 6 days later
· 6 days later
Published
- 2 days later
· 2 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| LinuxCNA (assigner) | 3.1 | High7.1 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N |
| NVDNVD · Received | 3.1 | High7.1 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N |
- EPSS (exploitation in 30 days)
- 0.17% · top 93% of all CVEs (12 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.1.
Affected products
- affected 09cfefb7fa70c3af011b0db0a513fd80b2f18abc – < 76f88650763a35cbf1384c65d66d096fa31cc58d
- affected 09cfefb7fa70c3af011b0db0a513fd80b2f18abc – < e8a916579e427af32f2de8213dfa23c5df6e6664
- affected 09cfefb7fa70c3af011b0db0a513fd80b2f18abc – < 39bb21a4bff0d70058bf752d7b5aa2e2ccc864a9
- affected 09cfefb7fa70c3af011b0db0a513fd80b2f18abc – < a65f49b6f7ece756394f8f0e85570020e7fd0e35
- affected 09cfefb7fa70c3af011b0db0a513fd80b2f18abc – < e483da960892c41fa7f0cf0d2fc2410d65a483d6
- affected 09cfefb7fa70c3af011b0db0a513fd80b2f18abc – < 018e9828eb523c638fa3d9bdf0fd4956b74555b2
- affected 5.19
- unaffected < 5.19
- unaffected 6.1.178 – ≤ 6.1.*
- unaffected 6.6.145 – ≤ 6.6.*
- unaffected 6.12.97 – ≤ 6.12.*
- unaffected 6.18.40 – ≤ 6.18.*
- unaffected 7.1.5 – ≤ 7.1.*
- unaffected 7.2 – ≤ *
References
References6
- https://git.kernel.org/stable/c/76f88650763a35cbf1384c65d66d096fa31cc58d (opens in a new tab)
- https://git.kernel.org/stable/c/e8a916579e427af32f2de8213dfa23c5df6e6664 (opens in a new tab)
- https://git.kernel.org/stable/c/39bb21a4bff0d70058bf752d7b5aa2e2ccc864a9 (opens in a new tab)
- https://git.kernel.org/stable/c/a65f49b6f7ece756394f8f0e85570020e7fd0e35 (opens in a new tab)
- https://git.kernel.org/stable/c/e483da960892c41fa7f0cf0d2fc2410d65a483d6 (opens in a new tab)
- https://git.kernel.org/stable/c/018e9828eb523c638fa3d9bdf0fd4956b74555b2 (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-59001 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
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[](https://cveledger.app/cve/CVE-2026-72043)Record last updated .