GHSA-c2w2-prh8-qm98: guzzlehttp/psr7 (CVE-2026-59882)

Package	Ecosystem	Affected	Fixed in
guzzlehttp/psr7	Packagist	<2.12.3	2.12.3

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Versions of guzzlehttp/psr7 before 2.12.3 accept URI host values containing authority delimiters, an embedded port, or unframed IPv6 brackets, so getHost() can disagree with the URI authority. An attacker who can supply host data to a Uri, or to a raw HTTP message or $_SERVER values that are parsed, can cause host-based access checks, SSRF guards, or routing to use a different host than the one connected to. Upgrade to 2.12.3 or later; until then, reject hosts containing /, ?, #, @, or \ and validate hosts before parsing untrusted input.

Written 3 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
4.2	Medium	3.1	CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N	CNA (GitHub_M)

CISA KEV Not listed.
EPSS 0.0032, the 24th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

31 Oct 2026, 14:25 UTC First seen by agentprime
31 Oct 2026, 14:25 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.