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Fencer Intel
medium 5.0

CVE-2011-4203 json

Moodle CRLF Injection Vulnerability in Calendar Component

published 2011-12-22 14 y ago modified 2026-06-16 4 mo ago also GHSA-4w8m-96v9-2c86 , EUVD-2022-2457

cvss
5.0
version 2.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.2%
EPSS 1.2% chance of exploitation in 30 days, percentile 67%
public exploits
0
none known

Summary

CRLF injection vulnerability in calendar/set.php in the Calendar component in Moodle 1.9.x before 1.9.15, 2.0.x before 2.0.6, 2.1.x before 2.1.3, and 2.2 allows remote attackers to inject arbitrary HTTP headers and conduct HTTP response splitting attacks via vectors involving the url variable.

Patch / fix

  • packagist moodle/moodle 1.9.15, 2.0.6, 2.1.3

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2011-4203 updated cvss 5.0

Moodle CRLF injection vulnerability in calendar/set.php

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

1.18% chance of exploitation in the next 30 days, higher than 67% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • penturalabs.wordpress.com http://penturalabs.wordpress.com/2011/12/13/advisory-crlf-injection-vulnerability-in-moodle/ referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:P/A:N

Affected packages

ecosystem package affected fixed in
packagist moodle/moodle
<1.9.15
>=2.0, <2.0.6
>=2.1, <2.1.3
1.9.15
2.0.6
2.1.3

Classification

Weakness
  • CWE-94 Improper Control of Generation of Code
  • CWE-113 Improper Neutralization of CRLF Sequences in HTTP Headers
  • CWE-93 Improper Neutralization of CRLF Sequences

References

Sources

Fencer Intel 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.