fzf vulnerable to denial of service through quadratic HTTP request-body accumulation

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

5.7 · CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-53433: 0.38% estimated exploitation activity in the next 30 days; percentile 31.85 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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.

Published by the source

1 Oct 2026, 20:24 UTC

Last modified by the source

1 Oct 2026, 20:45 UTC

Source last checked

26 Oct 2026, 15:29 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-mvmf-94v6-879g

2. Revision 2 · amended · 25 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GO-2026-6620

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# Patch Next advisory brief: CVE-2026-53433

Advisory: fzf vulnerable to denial of service through quadratic HTTP request-body accumulation
IDs: CVE-2026-53433, GHSA-mvmf-94v6-879g
Record: https://patchnext.com/advisories/cve-2026-53433 (revision 3, source checked 26 Oct 2026, 15:29 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/junegunn/fzf 0.73.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/junegunn/fzf: affected < 0.73.1; fixed in 0.73.1

## Suggested inspection (read-only)
- Go github.com/junegunn/fzf: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/junegunn/fzf.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GO-2026-6620 (OSV record GO-2026-6620 lists affected ranges: Go github.com/junegunn/fzf >=0 <0.73.1 (fixed))
- Verified: https://github.com/advisories/GHSA-mvmf-94v6-879g (GitHub-reviewed advisory GHSA-mvmf-94v6-879g lists affected ranges: Go github.com/junegunn/fzf >=0 <0.73.1)

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