Skip to content
Fencer Vulns
high 8.2

CVE-2026-13048 json

Data::MuForm::Localizer versions through 0.05 for Perl execute Perl from a message catalog header, reached at an arbitrary path because load_lexicon interpolates the language attribute into the catalog filename

published 2026-08-13 2 mo ago modified 2026-11-04 4 d ago also EUVD-2026-58117

cvss
8.2
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 46%
public exploits
0
none known

Summary

Data::MuForm::Localizer versions through 0.05 for Perl execute Perl from a message catalog header, reached at an arbitrary path because load_lexicon interpolates the language attribute into the catalog filename.

load_lexicon builds the catalog path by appending `Messages/$lang.po` to the directory holding Localizer.pm, where $lang is the language attribute, with no check that it names a bare locale tag. A value holding `../` segments walks out of the message directory, so any readable path with a `.po` suffix is loaded. While parsing the catalog, extract_header_msgstr takes the `Plural-Forms:` header, prefixes `$` to the bare words nplurals, plural and n, and passes the rest verbatim into a string that is evaluated: the nplurals form evaluates the header expression immediately, and the plural_code form compiles it into a subroutine whose body runs when a plural message is localized. A header of `nplurals=2; plural=(system('...'),0);` therefore runs that command as the catalog loads. The evaluation inherits strict, so an expression that assigns to an undeclared variable fails to compile, while one built from calls alone does not.

An application that sets the language attribute from request data, an Accept-Language header or a locale parameter, and an attacker who can place a file with a `.po` suffix and chosen contents at a readable path, together give code execution as the application user. The message expansion path is not affected: expand_named substitutes only the placeholder names the caller supplies, and _mangle_value returns the value unchanged.

Patch / fix

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
2 mo ago

Exploit prediction

0.56% chance of exploitation in the next 30 days, higher than 46% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 8.2 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N
CNA 3.1 8.2 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N

Classification

Weakness
  • CWE-95 Improper Neutralization of Directives in Dynamically Evaluated Code
  • CWE-22 Improper Limitation of a Pathname to a Restricted Directory

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.