How severe is CVE-2026-39376?

CVE-2026-39376 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-39376 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (25th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-39376?

CVE-2026-39376 affects Kagi Fastfeedparser. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-39376?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-39376 have an EU (EUVD) identifier?

Yes. CVE-2026-39376 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-19915.

When was CVE-2026-39376 published?

CVE-2026-39376 was published on 2026-04-07 and last updated on 2026-06-17.

CVE-2026-39376

CVE-2026-39376 is a high-severity vulnerability in Kagi Fastfeedparser with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-674.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 0% (25th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-19915
Weakness: CWE-674
Affected product: Kagi Fastfeedparser
Published: 2026-04-07
Last modified: 2026-06-17

Description

FastFeedParser is a high performance RSS, Atom and RDF parser. Prior to 0.5.10, when parse() fetches a URL that returns an HTML page containing a <meta http-equiv="refresh"> tag, it recursively calls itself with the redirect URL — with no depth limit, no visited-URL deduplication, and no redirect count cap. An attacker-controlled server that returns an infinite chain of HTML meta-refresh responses causes unbounded recursion, exhausting the Python call stack and crashing the process. This vulnerability can also be chained with the companion SSRF issue to reach internal network targets after bypassing the initial URL check. This vulnerability is fixed in 0.5.10.

Frequently asked questions

What is CVE-2026-39376?: FastFeedParser is a high performance RSS, Atom and RDF parser. Prior to 0.5.10, when parse() fetches a URL that returns an HTML page containing a <meta http-equiv="refresh"> tag, it recursively calls itself with the redirect URL — with no depth limit, no visited-URL deduplication, and no redirect count cap. An attacker-controlled server that returns an infinite chain of HTML meta-refresh responses causes unbounded recursion, exhausting the Python call stack and crashing the process. This vulnerability can also be chained with the companion SSRF issue to reach internal network targets after bypassing the initial URL check. This vulnerability is fixed in 0.5.10.
How severe is CVE-2026-39376?: CVE-2026-39376 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-39376 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (25th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-39376?: CVE-2026-39376 affects Kagi Fastfeedparser. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-39376?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-39376 have an EU (EUVD) identifier?: Yes. CVE-2026-39376 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-19915.
When was CVE-2026-39376 published?: CVE-2026-39376 was published on 2026-04-07 and last updated on 2026-06-17.

References

https://github.com/kagisearch/fastfeedparser/security/advisories/GHSA-4gx2-pc4f-wq37

Affected products (1)

cpe:2.3:a:kagi:fastfeedparser:*:*:*:*:*:python:*:*

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