Predictive Vulnerability Intelligence.

Product

  • Product
  • Pricing
  • Documentation

Company

  • About
  • Partnerships
  • Blog
  • Support

Legal

  • Terms
  • Privacy
  • Data Licensing

© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2020-26154

31
FAUCET Score

CVE-2020-26154 describes a critical buffer overflow vulnerability in libproxy versions up to 0.4.15, specifically within the url.cpp component, affecting products like Debian, Fedora, and openSUSE. This flaw can be triggered when a large PAC file is delivered without a Content-length header, leading to a CVSS score of 9.8 (Critical) due to its network-based attack vector, low complexity, and potential for complete compromise of confidentiality, integrity, and availability. While no active exploitation, public exploit code, or significant community discussion has been observed, the high severity warrants immediate patching.

Impacted Technologies

VendorProductVersion(s)CPE
<= 0.4.15CPE matchmatch criteria
cpe:2.3:a:libproxy_project:libproxy:*:*:*:*:*:*:*:*
32CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*
33CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
9.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
10.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.8CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
3.57%
Probability of exploitation in next 30 days
EPSS Percentile
88.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0357 is in the 80th percentile among its peer group of 36,862 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (6)

microsoftpatch availablevia msrc
Product: 19199-16823Fixed in: 0.4.17-5
microsoftpatch availablevia msrc
Product: cbl2 libproxy 0.4.17-5 on CBL Mariner 2.0Fixed in: 0.4.17-5
microsoftpatch availablevia msrc
Product: CBL Mariner 2.0 x64Fixed in: 0.4.17-5
microsoftpatch availablevia msrc
Product: CBL Mariner 2.0 ARMFixed in: 0.4.17-5
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: libproxy-0:0.4.15-5.5.el8_10
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8.8 Extended Update SupportFixed in: libproxy-0:0.4.15-5.4.el8_8
View patch

Vendor Advisories (3)

microsoft2022-Jan/CVE-2020-26154

CVE-2020-26154

Jan 11, 2022
microsoft2020-Sep/CVE-2020-26154Critical

url.cpp in libproxy through 0.4.15 is prone to a buffer overflow when PAC is enabled as demonstrated by a large PAC file that is delivered without a Content-length header.

Sep 8, 2020
redhatCVE-2020-26154Moderate

libproxy: sending more than 102400 bytes in PAC without a Content-Length present could result in buffer overflow

Jul 16, 2020

References

lists.opensuse.org / opensuse-security-announce/2020-10/msg00030.html
Issue TrackingThird Party Advisory
lists.opensuse.org / opensuse-security-announce/2020-10/msg00033.html
Issue TrackingThird Party Advisory
bugs.debian.org / 968366
Issue TrackingThird Party Advisory
github.com / libproxy/libproxy/pull/126
Third Party Advisory
lists.debian.org / debian-lts-announce/2020/11/msg00024.html
Mailing ListThird Party Advisory
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/3BID3HVHAF6DA3YJOFDBSAZSMR3ODNIW
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/WZVZXTFMFTSML3J6OOCDBDYH474BRJSW
debian.org / security/2020/dsa-4800
Third Party Advisory