CVE-2026-9170: IBM HTTP Server 8.5, and 9.0 is vulnerable to denial of service and a potential remote code execution due to i

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CRITICAL 9.8REMOTEDOWNGRADE

CVE-2026-9170 is a critical-severity flaw (CVSS 9.8) affecting http server. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

IBM HTTP Server 8.5, and 9.0 is vulnerable to denial of service and a potential remote code execution due to improper input validation.

Why this priority

Critical severity
Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 58%)
CISA exploited list	No
Weakness	CWE-94
Published	2026-05-26
Last modified	2026-07-20

Publisher (CNA): IBM Corporation · Vendor: ibm

Last updated 2026-07-20 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-26 18:16 UTCPublished CVE record published
2026-07-20 20:10 UTCUpdated Record last modified

ibm http server DOWNGRADE

Affected: 8.5.0.0 · 9.0.0.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 8.5.0.0

1. Check installed version

apt-cache policy http-server || rpm -q http-server || http-server --version

2. No fixed release: DOWNGRADE to a release before 8.5.0.0 (Debian / Ubuntu)

apt-cache madison http-server sudo apt install http-server=<VERSION_BEFORE_8.5.0.0> sudo apt-mark hold http-server

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

dnf --showduplicates list http-server sudo dnf downgrade http-server-<VERSION_BEFORE_8.5.0.0> sudo dnf versionlock add http-server

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-2026-9170?

http server: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-9170 being exploited?

CVE-2026-9170 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-2026-9170 affect?

CVE-2026-9170 affects http server. Severity is critical (CVSS 9.8). IBM HTTP Server 8.5, and 9.0 is vulnerable to denial of service and a potential remote code execution due to improper input validation.

How urgent is CVE-2026-9170?

Priority 50/100. Critical severity; Remotely exploitable, no login, no user action

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References

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