9.8
CRITICAL
CVE-2021-33913
Exim Libspf2 Remote Buffer Overflow
Description

libspf2 before 1.2.11 has a heap-based buffer overflow that might allow remote attackers to execute arbitrary code (via an unauthenticated e-mail message from anywhere on the Internet) with a crafted SPF DNS record, because of SPF_record_expand_data in spf_expand.c. The amount of overflowed data depends on the relationship between the length of an entire domain name and the length of its leftmost label. The vulnerable code may be part of the supply chain of a site's e-mail infrastructure (e.g., with additional configuration, Exim can use libspf2; the Postfix web site links to unofficial patches for use of libspf2 with Postfix; older versions of spfquery relied on libspf2) but most often is not.

INFO

Published Date :

Jan. 19, 2022, 6:15 p.m.

Last Modified :

Jan. 15, 2024, 5:15 p.m.

Remotely Exploitable :

Yes !

Impact Score :

5.9

Exploitability Score :

3.9
Affected Products

The following products are affected by CVE-2021-33913 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Libspf2_project libspf2
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2021-33913.

URL Resource
https://github.com/shevek/libspf2/tree/8131fe140704eaae695e76b5cd09e39bd1dd220b Third Party Advisory
https://lists.debian.org/debian-lts-announce/2022/01/msg00015.html Mailing List Third Party Advisory
https://nathanielbennett.com/blog/libspf2-cve-jan-2022-disclosure Exploit Third Party Advisory
https://security.gentoo.org/glsa/202401-22

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2021-33913 vulnerability anywhere in the article.

The following table lists the changes that have been made to the CVE-2021-33913 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • CVE Modified by [email protected]

    May. 14, 2024

    Action Type Old Value New Value
  • CVE Modified by [email protected]

    Jan. 15, 2024

    Action Type Old Value New Value
    Added Reference MITRE https://security.gentoo.org/glsa/202401-22 [No types assigned]
  • Initial Analysis by [email protected]

    Jan. 26, 2022

    Action Type Old Value New Value
    Added CVSS V2 NIST (AV:N/AC:M/Au:N/C:C/I:C/A:C)
    Added CVSS V3.1 NIST AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
    Changed Reference Type https://github.com/shevek/libspf2/tree/8131fe140704eaae695e76b5cd09e39bd1dd220b No Types Assigned https://github.com/shevek/libspf2/tree/8131fe140704eaae695e76b5cd09e39bd1dd220b Third Party Advisory
    Changed Reference Type https://lists.debian.org/debian-lts-announce/2022/01/msg00015.html No Types Assigned https://lists.debian.org/debian-lts-announce/2022/01/msg00015.html Mailing List, Third Party Advisory
    Changed Reference Type https://nathanielbennett.com/blog/libspf2-cve-jan-2022-disclosure No Types Assigned https://nathanielbennett.com/blog/libspf2-cve-jan-2022-disclosure Exploit, Third Party Advisory
    Added CWE NIST CWE-787
    Added CPE Configuration OR *cpe:2.3:a:libspf2_project:libspf2:*:*:*:*:*:*:*:* versions up to (excluding) 1.2.11
  • CVE Modified by [email protected]

    Jan. 21, 2022

    Action Type Old Value New Value
    Added Reference https://lists.debian.org/debian-lts-announce/2022/01/msg00015.html [No Types Assigned]
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2021-33913 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2021-33913 weaknesses.

Exploit Prediction

EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days.

2.46 }} 0.16%

score

0.90237

percentile

CVSS31 - Vulnerability Scoring System
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