How severe is CVE-2026-53433?

No CVSS score has been assigned to CVE-2026-53433 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-53433?

CVE-2026-53433 affects the following packages: github.com/junegunn/fzf (Go). Ecosystems affected: Go.

How do I fix CVE-2026-53433?

Update github.com/junegunn/fzf to 0.73.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-53433 is resolved across your whole dependency graph.

How do I detect CVE-2026-53433 in my Go dependencies?

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

How do I mitigate CVE-2026-53433 if there is no patch (or I can't update yet)?

Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Is CVE-2026-53433 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-53433 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-2026-53433?

CVE-2026-53433 has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 31th 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-2026-53433?

CVE-2026-53433 is classified as CWE-407 (CWE-407). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-53433 published, and has it been updated?

CVE-2026-53433 was published on June 30, 2026 and was last updated on October 21, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CVE-2026-53433: fzf DoS — Fixed in 0.73.1

Exploitation Status

No confirmed exploitation observed yet

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-2026-53433.

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs31th percentile — riskier than 31% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected

🐹github.com/junegunn/fzf

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

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.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/junegunn/fzf`	all versions	0.73.1`go get github.com/junegunn/fzf@v0.73.1`

Affected Products

1 product · 1 configurations

Application

fzfjunegunn

< 0.73.1

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/junegunn/fzf, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/junegunn/fzf to 0.73.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-53433 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

A flaw was found in fzf, a command-line fuzzy finder. When fzf is running in --listen mode (a non-default, opt-in feature), inefficient HTTP body processing using repeated string concatenation results in quadratic time complexity. A crafted POST request can monopolize the single-threaded HTTP server, causing denial of…

Workaround published by Red Hat

Do not use fzf's --listen mode in untrusted network environments. If --listen is required, restrict network access to the fzf listener port using firewall rules.

Source: Red Hat security advisory for CVE-2026-53433 (CC BY 4.0)

Frequently Asked Questions

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.

O3 Security · Impact-Aware SCA

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CVE-2026-53433 — fzf