CVE-2026-53433: fzf — Fix

Description

fzf is vulnerable to a Denial of Service (DoS) due to inefficient HTTP body processing in the --listen mode due to inefficient HTTP body processing using repeated string concatenation, resulting in quadratic time complexity (O(n²)). A crafted POST request with many small segments can trigger excessive CPU usage during request handling.This allows a single malicious request to monopolize the single‑threaded HTTP server, blocking all other clients and resulting in denial of service. This issue was fixed in version 0.73.1.

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CVSS v3.1 Score

7.5

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS — Exploit Prediction

0.0021

Probability of exploitation

0.12%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-407 CWE-407

Affected Products

Vendor	Product	Versions
junegunn	fzf	< 0.73.1

References

Advisories & Patches

https://github.com/junegunn/fzf/commit/7963a2c6586c0b9eaa89b8995de8f0e08cf8a4ce

Other References

https://cert.pl/en/posts/2026/06/CVE-2026-53432 https://github.com/junegunn/fzf

Frequently Asked Questions

What is CVE-2026-53433? +

fzf is vulnerable to a Denial of Service (DoS) due to inefficient HTTP body processing in the --listen mode due to inefficient HTTP body processing using repeated string concatenation, resulting in quadratic time complexity (O(n²)). A crafted POST request with many small segments can trigger excessive CPU usage during request handling.This allows a single malicious request to monopolize the single‑threaded HTTP server, blocking all other clients and resulting in denial of service. This issue was fixed in version 0.73.1. It has a CVSS v3.1 base score of 7.5 (HIGH).

How severe is CVE-2026-53433? +

CVE-2026-53433 has a CVSS v3.1 score of 7.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0021, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-53433? +

CVE-2026-53433 affects products from junegunn, specifically: fzf. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-53433? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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