CyberSecBulletin
CVE-2025-37991NVD status: Analyzed

Linux: Double Free

Published Updated By the CyberSecBulletin desk

CVE-2025-37991 is a high-severity double free vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 2a1aff3616b3b57aa4a5f8a7762cce1e82493fe6, 757ba4d17b868482837c566cfefca59e2296c608, ec4584495868bd465fe60a3f771915c0e7ce7951 as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.22% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to 2a1aff3616b3b57aa4a5f8a7762cce1e82493fe6 or 757ba4d17b868482837c566cfefca59e2296c608 or ec4584495868bd465fe60a3f771915c0e7ce7951 or 6c639af49e9e5615a8395981eaf5943fb40acd6f, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.4.294 or 5.10.238 or 5.15.182 or 6.1.138, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 2a1aff3616b3b57aa4a5f8a7762cce1e82493fe6; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 757ba4d17b868482837c566cfefca59e2296c608; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, ec4584495868bd465fe60a3f771915c0e7ce7951; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 6c639af49e9e5615a8395981eaf5943fb40acd6f; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 6a098c51d18ec99485668da44294565c43dbc106; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, cf21e890f56b7d0038ddaf25224e4f4c69ecd143; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, df3592e493d7f29bae4ffde9a9325de50ddf962e; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, de3629baf5a33af1919dec7136d643b0662e85ef; and 1 more ranges2a1aff3616b3b57aa4a5f8a7762cce1e82493fe6, 757ba4d17b868482837c566cfefca59e2296c608, ec4584495868bd465fe60a3f771915c0e7ce7951, 6c639af49e9e5615a8395981eaf5943fb40acd6f, 6a098c51d18ec99485668da44294565c43dbc106, cf21e890f56b7d0038ddaf25224e4f4c69ecd143
LinuxLinux Kernelbefore 5.4.294; 5.5 up to, but not including, 5.10.238; 5.11 up to, but not including, 5.15.182; 5.16 up to, but not including, 6.1.138; 6.2 up to, but not including, 6.6.90; 6.7 up to, but not including, 6.12.28; 6.13 up to, but not including, 6.14.6; 6.155.4.294, 5.10.238, 5.15.182, 6.1.138, 6.6.90, 6.12.28
DebianDebian Linux11.0Not stated

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Official description

In the Linux kernel, the following vulnerability has been resolved: parisc: Fix double SIGFPE crash Camm noticed that on parisc a SIGFPE exception will crash an application with a second SIGFPE in the signal handler. Dave analyzed it, and it happens because glibc uses a double-word floating-point store to atomically update function descriptors. As a result of lazy binding, we hit a floating-point store in fpe_func almost immediately. When the T bit is set, an assist exception trap occurs when when the co-processor encounters *any* floating-point instruction except for a double store of register %fr0. The latter cancels all pending traps. Let's fix this by clearing the Trap (T) bit in the FP status register before returning to the signal handler in userspace. The issue can be reproduced with this test program: root@parisc:~# cat fpe.c static void fpe_func(int sig, siginfo_t *i, void *v) { sigset_t set; sigemptyset(&set); sigaddset(&set, SIGFPE); sigprocmask(SIG_UNBLOCK, &set, NULL); printf("GOT signal %d with si_code %ld\n", sig, i->si_code); } int main() { struct sigaction action = { .sa_sigaction = fpe_func, .sa_flags = SA_RESTART|SA_SIGINFO }; sigaction(SIGFPE, &action, 0); feenableexcept(FE_OVERFLOW); return printf("%lf\n",1.7976931348623158E308*1.7976931348623158E308); } root@parisc:~# gcc fpe.c -lm root@parisc:~# ./a.out Floating point exception root@parisc:~# strace -f ./a.out execve("./a.out", ["./a.out"], 0xf9ac7034 /* 20 vars */) = 0 getrlimit(RLIMIT_STACK, {rlim_cur=8192*1024, rlim_max=RLIM_INFINITY}) = 0 ... rt_sigaction(SIGFPE, {sa_handler=0x1110a, sa_mask=[], sa_flags=SA_RESTART|SA_SIGINFO}, NULL, 8) = 0 --- SIGFPE {si_signo=SIGFPE, si_code=FPE_FLTOVF, si_addr=0x1078f} --- --- SIGFPE {si_signo=SIGFPE, si_code=FPE_FLTOVF, si_addr=0xf8f21237} --- +++ killed by SIGFPE +++ Floating point exception

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Double Free

The product calls free() twice on the same memory address.

How developers prevent this class of flaw

  • Choose a language that provides automatic memory management.
  • Ensure that each allocation is freed only once. After freeing a chunk, set the pointer to NULL to ensure the pointer cannot be freed again. In complicated error conditions, be sure that clean-up routines respect the state of allocation properly. If the language is object oriented, ensure that object destructors delete each chunk of memory only once.
  • Use a static analysis tool to find double free instances.

More Double Free vulnerabilities (CWE-415)

Timeline

  1. CVE record published.
  2. Record last changed materially (score, affected products, status or references).

References

Third-party and government advisories

Recent Double Free vulnerabilities

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