# CVE-2025-37991: parisc: Fix double SIGFPE crash

> A flaw in the Linux kernel parisc architecture causes a double SIGFPE crash, leading to application termination and denial of service.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 20 May 2025
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2025-37991, DEBIAN-CVE-2025-37991, GHSA-xp2h-p3fr-j2j5, ROOT-OS-DEBIAN-11-CVE-2025-37991, ROOT-OS-DEBIAN-12-CVE-2025-37991, ROOT-OS-UBUNTU-2204-CVE-2025-37991, ROOT-OS-UBUNTU-2404-CVE-2025-37991, UBUNTU-CVE-2025-37991

## What is CVE-2025-37991?

CVE-2025-37991 is a high-severity denial of service vulnerability in Debian Debian Linux, published on 20 May 2025. It can only be exploited from the same machine or local network, with no action from the victim.

### 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

Weakness: CWE-415 (Double Free)

## Which versions are affected by CVE-2025-37991?

It affects 2 products.


Products: Debian Debian Linux, Linux kernel.

## How do I fix CVE-2025-37991?

Apply the vendor's patch.

## Is CVE-2025-37991 being exploited?

There is no known exploitation of CVE-2025-37991 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-37991 and fix it if it is affected.

What it is: CVE-2025-37991 is a high-severity denial of service vulnerability in Debian Debian Linux, published on 20 May 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2025-37991 in the wild and no public exploit code.

Affected product: Debian Debian Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-37991/ (Markdown: https://insights.sbomify.com/CVE-2025-37991/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-37991
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-37991
- OSV: https://osv.dev/vulnerability/CVE-2025-37991

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-37991/
Summaries are generated and may contain mistakes; the official description above is the record.