CVE-2025-27820: A bug in PSL validation logic in Apache HttpClient 5.4.x disables domain checks, affecting cookie management a

This month

HIGH 7.5REMOTEWATCHLISTUPGRADEDOWNGRADE

CVE-2025-27820 is a high-severity flaw (CVSS 7.5) affecting httpclient, ontap tools. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A bug in PSL validation logic in Apache HttpClient 5.4.x disables domain checks, affecting cookie management and host name verification. Discovered by the Apache HttpClient team. Fixed in the 5.4.3 release

Why this priority

High severity
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.0% (top 38%)
CISA exploited list	No
Weakness	CWE-295
Published	2025-04-24
Last modified	2026-06-17

Publisher (CNA): Apache Software Foundation · Vendor: apache · netapp

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2025-04-24 12:15 UTCPublished CVE record published
2026-06-17 09:04 UTCUpdated Record last modified

apache httpclient UPGRADE

Affected: >= 5.4 and < 5.4.3

Fixed in: 5.4.3

Safe to downgrade to: a release before 5.4

1. Check installed version

apt-cache policy httpclient || rpm -q httpclient || httpclient --version

2. UPGRADE to 5.4.3 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade httpclient

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade httpclient

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 5.4 (Debian / Ubuntu)

apt-cache madison httpclient sudo apt install httpclient=<VERSION_BEFORE_5.4> sudo apt-mark hold httpclient

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list httpclient sudo dnf downgrade httpclient-<VERSION_BEFORE_5.4> sudo dnf versionlock add httpclient

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

netapp ontap tools DOWNGRADE

Affected: 10

Fixed in: no fixed release known

Safe to downgrade to: a release before 10

1. Check installed version

apt-cache policy ontap-tools || rpm -q ontap-tools || ontap-tools --version

2. No fixed release: DOWNGRADE to a release before 10 (Debian / Ubuntu)

apt-cache madison ontap-tools sudo apt install ontap-tools=<VERSION_BEFORE_10> sudo apt-mark hold ontap-tools

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list ontap-tools sudo dnf downgrade ontap-tools-<VERSION_BEFORE_10> sudo dnf versionlock add ontap-tools

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2025-27820?

httpclient: upgrade to 5.4.3; ontap tools: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2025-27820 being exploited?

CVE-2025-27820 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2025-27820 affect?

CVE-2025-27820 affects httpclient, ontap tools. Severity is high (CVSS 7.5). A bug in PSL validation logic in Apache HttpClient 5.4.x disables domain checks, affecting cookie management and host name verification. Discovered by the Apache HttpClient team. Fixed in the 5.4.3 release

How urgent is CVE-2025-27820?

Priority 52/100. High severity; Remotely exploitable, no login, no user action; On your watchlist

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References

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