CVE-2026-59882: guzzlehttp/psr7 is a PSR-7 HTTP message library implementation in PHP

Q: How do I fix CVE-2026-59882?

psr-7: upgrade to 2.12.3. Exact commands for each OS are on this page.

Q: Is CVE-2026-59882 being exploited?

CVE-2026-59882 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-2026-59882 affect?

CVE-2026-59882 affects psr-7. Severity is medium (CVSS 4.2). guzzlehttp/psr7 is a PSR-7 HTTP message library implementation in PHP. Prior to 2.12.3, Uri::assertValidHost() does not reject URI host components containing authority delimiters, embedded ports, or malformed IPv6 brackets, allowing Uri::ge

Q: How urgent is CVE-2026-59882?

Priority 21/100. No elevated risk signals yet.

Routine

MEDIUM 4.2UPGRADE

CVE-2026-59882 is a medium-severity flaw (CVSS 4.2) affecting psr-7. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

guzzlehttp/psr7 is a PSR-7 HTTP message library implementation in PHP. Prior to 2.12.3, Uri::assertValidHost() does not reject URI host components containing authority delimiters, embedded ports, or malformed IPv6 brackets, allowing Uri::getHost() to disagree with the URI authority used for security or routing decisions. This issue is fixed in version 2.12.3.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	4.2 (Medium)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.3% (top 76%)
CISA exploited list	No
Weakness	CWE-436
Published	2026-07-08
Last modified	2026-10-25

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

Last updated 2026-10-25 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-08 17:17 UTCPublished CVE record published
2026-10-25 17:10 UTCUpdated Record last modified

guzzlephp psr-7 UPGRADE

Affected: < 2.12.3

Fixed in: 2.12.3

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 2.12.3 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade 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-2026-59882?

psr-7: upgrade to 2.12.3. Exact commands for each OS are on this page.

Is CVE-2026-59882 being exploited?

CVE-2026-59882 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-2026-59882 affect?

CVE-2026-59882 affects psr-7. Severity is medium (CVSS 4.2). guzzlehttp/psr7 is a PSR-7 HTTP message library implementation in PHP. Prior to 2.12.3, Uri::assertValidHost() does not reject URI host components containing authority delimiters, embedded ports, or malformed IPv6 brackets, allowing Uri::ge

How urgent is CVE-2026-59882?

Priority 21/100. No elevated risk signals yet.

Software pages

PHP vulnerabilities

References

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