CVE-2026-56742: Cilium is a networking, observability, and security solution

Routine

MEDIUM 5.9UPGRADE

CVE-2026-56742 is a medium-severity flaw (CVSS 5.9) affecting cilium. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Cilium is a networking, observability, and security solution. Prior to 1.17.17, 1.18.11, and 1.19.5, Cilium clusters using Gateway API allow users with permissions to create or update namespaced HTTPRoutes to mirror HTTP traffic to any Service in any namespace, bypassing the ReferenceGrant authorization mechanism. Gateway API functionality is disabled by default. This issue is fixed in versions 1.17.17, 1.18.11, and 1.19.5.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	5.9 (Medium)
Attack vector	Adjacent network
Attack complexity	Low
Privileges needed	High
User interaction	None
EPSS exploit chance	0.2% (top 93%)
CISA exploited list	No
Weakness	CWE-862
Published	2026-07-15
Last modified	2026-07-17

Publisher (CNA): GitHub, Inc. · Vendor: cilium

Last updated 2026-07-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-15 20:17 UTCPublished CVE record published
2026-07-17 17:48 UTCUpdated Record last modified

cilium cilium UPGRADE

Affected: < 1.17.17 · >= 1.18.0 and < 1.18.11 · >= 1.19.0 and < 1.19.5

Fixed in: 1.17.17, 1.18.11, 1.19.5

Safe to downgrade to: a release before 1.18.0

1. Check installed version

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

2. UPGRADE to 1.17.17 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade cilium

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 1.18.0 (Debian / Ubuntu)

apt-cache madison cilium sudo apt install cilium=<VERSION_BEFORE_1.18.0> sudo apt-mark hold cilium

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

dnf --showduplicates list cilium sudo dnf downgrade cilium-<VERSION_BEFORE_1.18.0> sudo dnf versionlock add cilium

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-2026-56742?

cilium: upgrade to 1.17.17, 1.18.11, 1.19.5. Exact commands for each OS are on this page.

Is CVE-2026-56742 being exploited?

CVE-2026-56742 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-2026-56742 affect?

CVE-2026-56742 affects cilium. Severity is medium (CVSS 5.9). Cilium is a networking, observability, and security solution. Prior to 1.17.17, 1.18.11, and 1.19.5, Cilium clusters using Gateway API allow users with permissions to create or update namespaced HTTPRoutes to mirror HTTP traffic to any Serv

How urgent is CVE-2026-56742?

Priority 22/100. No elevated risk signals yet.

Related CVEs

CVE-2026-49445 CRITICAL 9.2 UPGRADE Cilium is a networking, observability, and security solution
CVE-2026-56743 MEDIUM 5.4 UPGRADE Cilium is a networking, observability, and security solution

References

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