CVE-2025-71109: Linux kernel · MIPS: ftrace: Fix memory corruption when kernel is located beyond 32 bits
Affects Linux kernelSource CVE Database V5
Not known to be exploited · CVSS 7.1 High · fixed in e3e33ac2eb69d595079a1a1e444c2fb98efdd42d : patch Linux kernel soon.
Data as of 26 Oct 2026, 14:18 UTC
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 13% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in e3e33ac2eb69d595079a1a1e444c2fb98efdd42d, 36dac9a3dda1f2bae343191bc16b910c603cac25, 9cfda98cf02eacfa6b09076e98bd479fd73407c2 +1
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 14 Jan 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade Linux kernel to e3e33ac2eb69d595079a1a1e444c2fb98efdd42d, 36dac9a3dda1f2bae343191bc16b910c603cac25, 9cfda98cf02eacfa6b09076e98bd479fd73407c2 or 7f39b9d0e86ed6236b9a5fb67616ab1f76c4f150.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in– |
Description
In the Linux kernel, the following vulnerability has been resolved: MIPS: ftrace: Fix memory corruption when kernel is located beyond 32 bits Since commit e424054000878 ("MIPS: Tracing: Reduce the overhead of dynamic Function Tracer"), the macro UASM_i_LA_mostly has been used, and this macro can generate more than 2 instructions. At the same time, the code in ftrace assumes that no more than 2 instructions can be generated, which is why it stores them in an int[2] array. However, as previously noted, the macro UASM_i_LA_mostly (and now UASM_i_LA) causes a buffer overflow when _mcount is beyond 32 bits. This leads to corruption of the variables located in the __read_mostly section. This corruption was observed because the variable __cpu_primary_thread_mask was corrupted, causing a hang very early during boot. This fix prevents the corruption by avoiding the generation of instructions if they could exceed 2 instructions in length. Fortunately, insn_la_mcount is only used if the instrumented code is located outside the kernel code section, so dynamic ftrace can still be used, albeit in a more limited scope. This is still preferable to corrupting memory and/or crashing the kernel.
References
- git.kernel.org/stable/c/9cfda98cf02eacfa6b09076e98bd479fd73407c2 (opens in a new tab)
- git.kernel.org/stable/c/e3e33ac2eb69d595079a1a1e444c2fb98efdd42d (opens in a new tab)
- git.kernel.org/stable/c/7f39b9d0e86ed6236b9a5fb67616ab1f76c4f150 (opens in a new tab)
- git.kernel.org/stable/c/36dac9a3dda1f2bae343191bc16b910c603cac25 (opens in a new tab)