How severe is CVE-2026-67339?

No CVSS score has been assigned to CVE-2026-67339 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-67339?

CVE-2026-67339 affects the following packages: guzzlehttp/guzzle (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2026-67339?

Update guzzlehttp/guzzle to 7.14.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-67339 is resolved across your whole dependency graph.

How do I detect CVE-2026-67339 in my Packagist dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for guzzlehttp/guzzle, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-67339 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against CVE-2026-67339?

O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-67339 can be triaged on real exposure rather than presence alone.

Is CVE-2026-67339 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-67339 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-67339?

CVE-2026-67339 has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 14th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-67339?

CVE-2026-67339 is classified as Information Exposure (CWE-200). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-67339 published, and has it been updated?

CVE-2026-67339 was published on August 1, 2026 and was last updated on September 10, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐘 Packagist

Not in CISA KEV

CVE-2026-67339 — guzzlehttp/guzzle

CVE-2026-67339 is a Information Exposure vulnerability in guzzlehttp/guzzle. A fix is available for guzzlehttp/guzzle — see the affected versions and patch details below.

guzzlehttp/guzzle before 7.14.2 Proxy-Authorization Header Disclosure

Also known asGHSA-94pj-82f3-465w

Published

Aug 1, 2026

Updated

Sep 10, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Sep 18, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-67339.

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs14th percentile — riskier than 14% of all scored CVEsHighest risk

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Real-World Exposure

1 pkg affected

🐘guzzlehttp/guzzle

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.

Description

guzzlehttp/guzzle versions before 7.14.2 fail to properly isolate Proxy-Authorization headers from origin servers in cURL handlers. Attackers can capture proxy credentials through origin server access logs when requests are redirected, bypassed, or sent through SOCKS proxies that Guzzle misclassifies as direct connections.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`guzzlehttp/guzzle`	all versions	7.14.2`composer require guzzlehttp/guzzle:^7.14.2`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for guzzlehttp/guzzle, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update guzzlehttp/guzzle to 7.14.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-67339 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-67339 can be triaged on real exposure rather than presence alone.

Tailored to CVE-2026-67339. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

O3 Security · Impact-Aware SCA

Is CVE-2026-67339 in your dependencies?

O3 Security finds CVE-2026-67339 across Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.

Scan my dependencies How O3 SCA works