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CVE-2021-37147

Request Smuggling - LF line ending

7.5 HighFix available

Improper input validation vulnerability in header parsing of Apache Traffic Server allows an attacker to smuggle requests. This issue affects Apache Traffic Server 8.0.0 to 8.1.2 and 9.0.0 to 9.1.0.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
High
Availability
None

Exploit likelihood

2.52%Up 2.1 points since Nov 4, 2021
90%50%10%1%

What each source reports

NVD Score used7.5

Improper input validation vulnerability in header parsing of Apache Traffic Server allows an attacker to smuggle requests. This issue affects Apache Traffic Server 8.0.0 to 8.1.2 and 9.0.0 to 9.1.0.

Record
CVE-2021-37147
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
CVSS 2.0
5.0 MediumAV:N/AC:L/Au:N/C:N/I:P/A:N
Weakness
CWE-20, CWE-444
Updated
2026-11-02
CVE ListNo score

Request Smuggling - LF line ending

Improper input validation vulnerability in header parsing of Apache Traffic Server allows an attacker to smuggle requests. This issue affects Apache Traffic Server 8.0.0 to 8.1.2 and 9.0.0 to 9.1.0.

Record
CVE-2021-37147
Weakness
CWE-20, CWE-444
Updated
2026-11-02
EUVDEUVD-2021-23721No score

Improper input validation vulnerability in header parsing of Apache Traffic Server allows an attacker to smuggle requests. This issue affects Apache Traffic Server 8.0.0 to 8.1.2 and 9.0.0 to 9.1.0.

Record
EUVD-2021-23721
Updated
2026-11-03
GitHub AdvisoriesGHSA-2c64-8v4j-vw3m7.5

Improper input validation vulnerability in header parsing of Apache Traffic Server allows an...

Improper input validation vulnerability in header parsing of Apache Traffic Server allows an attacker to smuggle requests. This issue affects Apache Traffic Server 8.0.0 to 8.1.2 and 9.0.0 to 9.1.0.

Record
GHSA-2c64-8v4j-vw3m
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Weakness
CWE-20
Updated
2026-11-02
OSV7.5

Improper input validation vulnerability in header parsing of Apache Traffic Server allows an attacker to smuggle requests. This issue affects Apache Traffic Server 8.0.0 to 8.1.2 and 9.0.0 to 9.1.0.

Record
CVE-2021-37147
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Updated
2026-11-02
OSVDEBIAN-CVE-2021-371477.5

Improper input validation vulnerability in header parsing of Apache Traffic Server allows an attacker to smuggle requests. This issue affects Apache Traffic Server 8.0.0 to 8.1.2 and 9.0.0 to 9.1.0.

Record
DEBIAN-CVE-2021-37147
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Updated
2026-11-02
OSVOESA-2021-14379.8

trafficserver security update

Apache Traffic Server is an OpenSource HTTP / HTTPS / HTTP/2 / QUIC reverse, forward and transparent proxy and cache.

Security Fix(es):

Improper input validation vulnerability in header parsing of Apache Traffic Server allows an attacker to smuggle requests. This issue affects Apache Traffic Server 8.0.0 to 8.1.2 and 9.0.0 to 9.1.0.(CVE-2021-37147)

Improper Input Validation vulnerability in header parsing of Apache Traffic Server allows an attacker to smuggle requests. This issue affects Apache Traffic Server 8.0.0 to 8.1.2 and 9.0.0 to 9.1.0.(CVE-2021-37149)

Improper Input Validation vulnerability in accepting socket connections in Apache Traffic Server allows an attacker to make the server stop accepting new connections. This issue affects Apache Traffic Server 5.0.0 to 9.1.0.(CVE-2021-41585)

Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') vulnerability in the stats-over-http plugin of Apache Traffic Server allows an attacker to overwrite memory. This issue affects Apache Traffic Server 9.1.0.(CVE-2021-43082)

Record
OESA-2021-1437
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2021-371477.5

Improper input validation vulnerability in header parsing of Apache Traffic Server allows an attacker to smuggle requests. This issue affects Apache Traffic Server 8.0.0 to 8.1.2 and 9.0.0 to 9.1.0.

Record
UBUNTU-CVE-2021-37147
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
trafficserver
Debian:12
before 9.1.1+ds-1
9.1.1+ds-1
trafficserver
Debian:10
From an advisory covering 6 CVEs
before 8.0.2+ds-1+deb10u6, plus listed versions
8.0.2+ds-18.0.2+ds-1+deb10u18.0.2+ds-1+deb10u28.0.2+ds-1+deb10u38.0.2+ds-1+deb10u48.0.2+ds-1+deb10u5
8.0.2+ds-1+deb10u6
trafficserver
Debian:11
From an advisory covering 6 CVEs
before 8.1.1+ds-1.1+deb11u1, plus listed versions
8.1.1+ds-1.1
8.1.1+ds-1.1+deb11u1
trafficserver
openEuler:20.03-LTS-SP1
From an advisory covering 4 CVEs
before 9.1.0-4.oe1
9.1.0-4.oe1
trafficserver
openEuler:20.03-LTS-SP2
From an advisory covering 4 CVEs
before 9.1.0-4.oe1
9.1.0-4.oe1
trafficserver
Ubuntu:16.04:LTS
All versions, plus listed versions
5.3.0-2ubuntu15.3.0-2ubuntu2
None known
trafficserver
Ubuntu:18.04:LTS
All versions, plus listed versions
7.0.0-57.1.2+ds-27.1.2+ds-2build17.1.2+ds-3
None known
trafficserver
Ubuntu:Pro:20.04:LTS
All versions, plus listed versions
8.0.5+ds-18.0.5+ds-28.0.5+ds-2build18.0.5+ds-2ubuntu18.0.5+ds-38.0.5+ds-3ubuntu0.1~esm1
None known

History

History
RecordedChangedSources
affected, facts
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-37147 is a high vulnerability (CVSS 7.5) in Apache Traffic Server, published November 3, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 2.52%, the 85th percentile. Fixed in trafficserver 9.1.1+ds-1.

References

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