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CVE-2025-55702

Apache Traffic Server: An unread Expect: 100-continue request body is framed as a new request

7.0 High

When a client sends a POST with Expect: 100-continue and the origin answers before reading the body, Apache Traffic Server parses the unread body left on the client connection as the next request. An attacker behind a front-end proxy that shares connections to Traffic Server can use this to smuggle requests past the front end and desynchronize responses for other users.

This issue affects Apache Traffic Server: from 8.0.0 through 8.1.11, from 9.0.0 through 9.2.15, from 10.0.0 through 10.1.4, 10.2.0.

Users are recommended to upgrade to version 9.2.16, 10.1.5, or 10.2.1, which fix the issue.

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
None
Availability
None

Exploit likelihood

0.33%Up 0.1 points since Oct 22, 2026
90%50%10%1%

What each source reports

CVE List Score used 7.0

Apache Traffic Server: An unread Expect: 100-continue request body is framed as a new request

When a client sends a POST with Expect: 100-continue and the origin answers before reading the body, Apache Traffic Server parses the unread body left on the client connection as the next request. An attacker behind a front-end proxy that shares connections to Traffic Server can use this to smuggle requests past the front end and desynchronize responses for other users.

This issue affects Apache Traffic Server: from 8.0.0 through 8.1.11, from 9.0.0 through 9.2.15, from 10.0.0 through 10.1.4, 10.2.0.

Users are recommended to upgrade to version 9.2.16, 10.1.5, or 10.2.1, which fix the issue.

Record
CVE-2025-55702
CVSS 4.0
7.0 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N
CVSS 3.1
8.7 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N
Weakness
CWE-444
Updated
2026-11-02
EUVDEUVD-2025-211168 7.0

When a client sends a POST with Expect: 100-continue and the origin answers before reading the body, Apache Traffic Server parses the unread body left on the client connection as the next request. An attacker behind a front-end proxy that shares connections to Traffic Server can use this to smuggle requests past the front end and desynchronize responses for other users.

This issue affects Apache Traffic Server: from 8.0.0 through 8.1.11, from 9.0.0 through 9.2.15, from 10.0.0 through 10.1.4, 10.2.0.

Users are recommended to upgrade to version 9.2.16, 10.1.5, or 10.2.1, which fix the issue.

Record
EUVD-2025-211168
CVSS 4.0
7.0 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-5vqp-jf47-frjg 7.0

When a client sends a POST with Expect: 100-continue and the origin answers before reading the...

When a client sends a POST with Expect: 100-continue and the origin answers before reading the body, Apache Traffic Server parses the unread body left on the client connection as the next request. An attacker behind a front-end proxy that shares connections to Traffic Server can use this to smuggle requests past the front end and desynchronize responses for other users.

This issue affects Apache Traffic Server: from 8.0.0 through 8.1.11, from 9.0.0 through 9.2.15, from 10.0.0 through 10.1.4, 10.2.0.

Users are recommended to upgrade to version 9.2.16, 10.1.5, or 10.2.1, which fix the issue.

Record
GHSA-5vqp-jf47-frjg
CVSS 4.0
7.0 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1
8.7 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N
Weakness
CWE-444
Updated
2026-11-02
NVD 7.0

When a client sends a POST with Expect: 100-continue and the origin answers before reading the body, Apache Traffic Server parses the unread body left on the client connection as the next request. An attacker behind a front-end proxy that shares connections to Traffic Server can use this to smuggle requests past the front end and desynchronize responses for other users.

This issue affects Apache Traffic Server: from 8.0.0 through 8.1.11, from 9.0.0 through 9.2.15, from 10.0.0 through 10.1.4, 10.2.0.

Users are recommended to upgrade to version 9.2.16, 10.1.5, or 10.2.1, which fix the issue.

Record
CVE-2025-55702
CVSS 4.0
7.0 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1
8.7 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N
Weakness
CWE-444
Updated
2026-11-02
OSVDEBIAN-CVE-2025-55702 7.0

When a client sends a POST with Expect: 100-continue and the origin answers before reading the body, Apache Traffic Server parses the unread body left on the client connection as the next request. An attacker behind a front-end proxy that shares connections to Traffic Server can use this to smuggle requests past the front end and desynchronize responses for other users. This issue affects Apache Traffic Server: from 8.0.0 through 8.1.11, from 9.0.0 through 9.2.15, from 10.0.0 through 10.1.4, 10.2.0. Users are recommended to upgrade to version 9.2.16, 10.1.5, or 10.2.1, which fix the issue.

Record
DEBIAN-CVE-2025-55702
CVSS 4.0
7.0 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Updated
2026-11-02
OSVUBUNTU-CVE-2025-55702 7.0

When a client sends a POST with Expect: 100-continue and the origin answers before reading the body, Apache Traffic Server parses the unread body left on the client connection as the next request. An attacker behind a front-end proxy that shares connections to Traffic Server can use this to smuggle requests past the front end and desynchronize responses for other users. This issue affects Apache Traffic Server: from 8.0.0 through 8.1.11, from 9.0.0 through 9.2.15, from 10.0.0 through 10.1.4, 10.2.0. Users are recommended to upgrade to version 9.2.16, 10.1.5, or 10.2.1, which fix the issue.

Record
UBUNTU-CVE-2025-55702
CVSS 4.0
7.0 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N
CVSS 3.1
8.7 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
trafficserver
Debian:12
 All versions, plus listed versions
9.2.0+ds-29.2.0+ds-2+deb12u19.2.1+ds-19.2.2+ds-19.2.3+ds-1
Show 9 moreShow less
9.2.3+ds-1+deb12u19.2.4+ds-0+deb12u19.2.4+ds-19.2.4+ds-29.2.5+ds-0+deb12u19.2.5+ds-0+deb12u29.2.5+ds-0+deb12u39.2.5+ds-0+deb12u49.2.5+ds-1
 None known
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
trafficserver
Ubuntu:Pro:22.04:LTS
 All versions, plus listed versions
8.1.1+ds-1.19.1.1+ds-2build19.1.1+ds-2ubuntu0.1~esm19.1.1+ds-2ubuntu0.19.1.1+ds-2ubuntu0.1+esm1
 None known
trafficserver
Ubuntu:24.04:LTS
 All versions, plus listed versions
9.2.1+ds-1build19.2.2+ds-19.2.3+ds-19.2.3+ds-1+deb12u19.2.3+ds-1+deb12u1build19.2.3+ds-1+deb12u1build39.2.3+ds-1+deb12u1build49.2.3+ds-1+deb12u1ubuntu0.1
 None known

History

History
RecordedChangedSources
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

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

In short

CVE-2025-55702 is a high vulnerability (CVSS 7.0) in Apache Software Foundation Traffic Server, published October 21, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.33%, the 25th percentile. No source names a fixed version.

References

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