CVE-2025-29904: In JetBrains Ktor before 3.1.1 an HTTP Request Smuggling was possible

Q: How do I fix CVE-2025-29904?

ktor: upgrade to 3.1.1. Exact commands for each OS are on this page.

Q: Is CVE-2025-29904 being exploited?

CVE-2025-29904 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2025-29904 affect?

CVE-2025-29904 affects ktor. Severity is medium (CVSS 5.3). In JetBrains Ktor before 3.1.1 an HTTP Request Smuggling was possible

Q: How urgent is CVE-2025-29904?

Priority 30/100. Remotely exploitable, no login, no user action

Routine

MEDIUM 5.3REMOTEUPGRADE

CVE-2025-29904 is a medium-severity flaw (CVSS 5.3) affecting ktor. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In JetBrains Ktor before 3.1.1 an HTTP Request Smuggling was possible

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.3% (top 74%)
CISA exploited list	No
Weakness	CWE-444
Published	2025-03-12
Last modified	2026-06-17

Publisher (CNA): JetBrains s.r.o. · Vendor: jetbrains

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

Am I affected?

Timeline

2025-03-12 13:15 UTCPublished CVE record published
2026-06-17 09:05 UTCUpdated Record last modified

jetbrains ktor UPGRADE

Affected: < 3.1.1

Fixed in: 3.1.1

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 3.1.1 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade ktor

Note

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

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-2025-29904?

ktor: upgrade to 3.1.1. Exact commands for each OS are on this page.

Is CVE-2025-29904 being exploited?

CVE-2025-29904 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-2025-29904 affect?

CVE-2025-29904 affects ktor. Severity is medium (CVSS 5.3). In JetBrains Ktor before 3.1.1 an HTTP Request Smuggling was possible

How urgent is CVE-2025-29904?

Priority 30/100. Remotely exploitable, no login, no user action

Related CVEs

CVE-2024-49580 MEDIUM 5.3 UPGRADE In JetBrains Ktor before 2.3.13 improper caching in HttpCache Plugin could lead to response information disclo

References

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