CVE-2023-30536: slim/psr7 is a PSR-7 implementation for use with Slim 4

Q: How do I fix CVE-2023-30536?

slim psr-7: upgrade to 1.6.1. Exact commands for each OS are on this page.

Q: Is CVE-2023-30536 being exploited?

CVE-2023-30536 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-2023-30536 affect?

CVE-2023-30536 affects slim psr-7. Severity is medium (CVSS 6.5). slim/psr7 is a PSR-7 implementation for use with Slim 4. In versions prior to 1.6.1 an attacker could sneak in a newline (\n) into both the header names and values. While the specification states that \r\n\r\n is used to terminate the heade

Q: How urgent is CVE-2023-30536?

Priority 41/100. Remotely exploitable, no login, no user action

This month

MEDIUM 6.5REMOTEUPGRADE

CVE-2023-30536 is a medium-severity flaw (CVSS 6.5) affecting slim psr-7. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

slim/psr7 is a PSR-7 implementation for use with Slim 4. In versions prior to 1.6.1 an attacker could sneak in a newline (\n) into both the header names and values. While the specification states that \r\n\r\n is used to terminate the header list, many servers in the wild will also accept \n\n. An attacker that is able to control the header names that are passed to Slilm-Psr7 would be able to intentionally craft invalid messages, possibly causing

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.7% (top 45%)
CISA exploited list	No
Weakness	CWE-436
Published	2023-04-17
Last modified	2026-06-17

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

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

Am I affected?

Timeline

2023-04-17 22:15 UTCPublished CVE record published
2026-06-17 05:54 UTCUpdated Record last modified

slimframework slim psr-7 UPGRADE

Affected: < 1.6.1

Fixed in: 1.6.1

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy slim-psr-7 || rpm -q slim-psr-7 || slim-psr-7 --version

2. UPGRADE to 1.6.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade slim-psr-7

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade slim-psr-7

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-2023-30536?

slim psr-7: upgrade to 1.6.1. Exact commands for each OS are on this page.

Is CVE-2023-30536 being exploited?

CVE-2023-30536 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-2023-30536 affect?

CVE-2023-30536 affects slim psr-7. Severity is medium (CVSS 6.5). slim/psr7 is a PSR-7 implementation for use with Slim 4. In versions prior to 1.6.1 an attacker could sneak in a newline (\n) into both the header names and values. While the specification states that \r\n\r\n is used to terminate the heade

How urgent is CVE-2023-30536?

Priority 41/100. Remotely exploitable, no login, no user action

References

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