CVE-2021-27577

Incorrect handling of url fragment leads to cache poisoning

7.5 HighFix available

Incorrect handling of url fragment vulnerability of Apache Traffic Server allows an attacker to poison the cache. This issue affects Apache Traffic Server 7.0.0 to 7.1.12, 8.0.0 to 8.1.1, 9.0.0 to 9.0.1.

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

3.45%Up 3.0 points since Jun 30, 2021

What each source reports

NVD Score used 7.5

Record: CVE-2021-27577
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-444
Updated: 2026-11-02

CVE List No score

Incorrect handling of url fragment leads to cache poisoning

Record: CVE-2021-27577
Weakness: CWE-444
Updated: 2026-11-02

EUVDEUVD-2021-14326 No score

Record: EUVD-2021-14326
Updated: 2026-11-03

GitHub AdvisoriesGHSA-m6m2-j477-jfg8 No score

Incorrect handling of url fragment vulnerability of Apache Traffic Server allows an attacker to...

Record: GHSA-m6m2-j477-jfg8
Weakness: CWE-444
Updated: 2026-11-02

OSV 7.5

Record: CVE-2021-27577
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-2021-27577 7.5

Record: DEBIAN-CVE-2021-27577
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

OSVUBUNTU-CVE-2021-27577 7.5

Record: UBUNTU-CVE-2021-27577
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
Package	Affected	Fixed
`trafficserver` Debian:12	before 8.1.1+ds-1.1	8.1.1+ds-1.1
`trafficserver` Debian:10 From an advisory covering 5 CVEs	before 8.0.2+ds-1+deb10u5, 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+deb10u4	8.0.2+ds-1+deb10u5
`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
Recorded	Changed	Sources
Nov 6, 2026	affected, facts
Nov 3, 2026	aliases	EUVD
Nov 2, 2026	first indexed	CVE List, GitHub Advisories, NVD, OSV

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

In short

CVE-2021-27577 is a high vulnerability (CVSS 7.5) in Apache Traffic Server, published June 29, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 3.45%, the 89th percentile. Fixed in trafficserver 8.1.1+ds-1.1.

References

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