Vulnerabilities
Misconfiguration
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CVE Vulnerabilities

CVE-2021-25220

Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

Published: Mar 23, 2022 | Modified: Nov 21, 2024
CVSS 3.x
6.8
MEDIUM
Source:
NVD
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:H/A:N
CVSS 2.x
4 MEDIUM
AV:N/AC:L/Au:S/C:N/I:P/A:N
RedHat/V2
RedHat/V3
6.8 MODERATE
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:H/A:N
Ubuntu
MEDIUM
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Additional information
NVDhttps://nvd.nist.gov/vuln/detail/CVE-2021-25220
CWEhttps://cwe.mitre.org/data/definitions/444.html

BIND 9.11.0 -> 9.11.36 9.12.0 -> 9.16.26 9.17.0 -> 9.18.0 BIND Supported Preview Editions: 9.11.4-S1 -> 9.11.36-S1 9.16.8-S1 -> 9.16.26-S1 Versions of BIND 9 earlier than those shown - back to 9.1.0, including Supported Preview Editions - are also believed to be affected but have not been tested as they are EOL. The cache could become poisoned with incorrect records leading to queries being made to the wrong servers, which might also result in false information being returned to clients.

Weakness

The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.

Affected Software

NameVendorStart VersionEnd Version
BindIsc9.11.0 (including)9.11.37 (excluding)
BindIsc9.11.4 (including)9.11.37 (excluding)
BindIsc9.12.0 (including)9.16.27 (excluding)
BindIsc9.16.8 (including)9.16.27 (excluding)
BindIsc9.17.0 (including)9.18.0 (including)
Red Hat Enterprise Linux 6 Extended Lifecycle Support - EXTENSIONRedHatbind-32:9.8.2-0.68.rc1.el6_10.17*
Red Hat Enterprise Linux 7RedHatbind-32:9.11.4-26.P2.el7_9.13*
Red Hat Enterprise Linux 8RedHatbind9.16-32:9.16.23-0.9.el8.1*
Red Hat Enterprise Linux 8RedHatbind-32:9.11.36-5.el8*
Red Hat Enterprise Linux 8RedHatbind-32:9.11.36-5.el8*
Red Hat Enterprise Linux 8.2 Advanced Update SupportRedHatbind-32:9.11.13-6.el8_2.11*
Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update SupportRedHatbind-32:9.11.26-4.el8_4.8*
Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-OnRedHatbind-32:9.11.26-4.el8_4.8*
Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update SupportRedHatbind9.16-32:9.16.23-0.7.el8_6.9*
Red Hat Enterprise Linux 8.6 Extended Update SupportRedHatbind-32:9.11.36-3.el8_6.7*
Red Hat Enterprise Linux 8.6 Extended Update SupportRedHatdhcp-12:4.3.6-47.el8_6.2*
Red Hat Enterprise Linux 8.6 Telecommunications Update ServiceRedHatbind9.16-32:9.16.23-0.7.el8_6.9*
Red Hat Enterprise Linux 8.6 Update Services for SAP SolutionsRedHatbind9.16-32:9.16.23-0.7.el8_6.9*
Red Hat Enterprise Linux 9RedHatbind-32:9.16.23-5.el9_1*
Red Hat Enterprise Linux 9RedHatdhcp-12:4.4.2-17.b1.el9*
Red Hat Enterprise Linux 9.0 Update Services for SAP SolutionsRedHatbind-32:9.16.23-1.el9_0.11*
Bind9Ubuntubionic*
Bind9Ubuntudevel*
Bind9Ubuntuesm-infra-legacy/trusty*
Bind9Ubuntuesm-infra/bionic*
Bind9Ubuntuesm-infra/focal*
Bind9Ubuntuesm-infra/xenial*
Bind9Ubuntufocal*
Bind9Ubuntuimpish*
Bind9Ubuntujammy*
Bind9Ubuntutrusty/esm*
Bind9Ubuntuupstream*

Extended Description

HTTP requests or responses (“messages”) can be malformed or unexpected in ways that cause web servers or clients to interpret the messages in different ways than intermediary HTTP agents such as load balancers, reverse proxies, web caching proxies, application firewalls, etc. For example, an adversary may be able to add duplicate or different header fields that a client or server might interpret as one set of messages, whereas the intermediary might interpret the same sequence of bytes as a different set of messages. For example, discrepancies can arise in how to handle duplicate headers like two Transfer-encoding (TE) or two Content-length (CL), or the malicious HTTP message will have different headers for TE and CL. The inconsistent parsing and interpretation of messages can allow the adversary to “smuggle” a message to the client/server without the intermediary being aware of it. This weakness is usually the result of the usage of outdated or incompatible HTTP protocol versions in the HTTP agents.

Potential Mitigations

References

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