CVE
PapaParse denial of service in CSV parser via quoted fields
Affects PapaParse before 5.7.1 when Papa.parse() receives a delimiter-free quoted CSV. Fixed in 5.7.1.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 5.7.1
- Who is exposed
- Not reported
Do first: Upgrade to a fixed version: 5.7.1.
- Last modified
- Whether it needs action now or is a reference record, by fixed rules, with why. Last checked is when cve.now last re-read it.What do these mean? →
- Reference
- Last checked
- FIRST's estimate of the chance attackers exploit it in the next 30 days, updated daily.What do these mean? →
- 0.68% · 52nd percentile
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 29/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Unclear
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: yes
- Technical impact: partial
Summary
PapaParse, a CSV parsing library, is affected: remote attackers who need no login can send specially crafted quoted CSV input to its parse function and make it consume excessive CPU. This can block the Node.js event loop or freeze a browser tab, causing denial of service.
Read the original description
PapaParse before 5.7.1 contains an inefficient algorithmic complexity vulnerability that allows remote unauthenticated attackers to cause denial of service by submitting delimiter-free quoted CSV input to Papa.parse(). Attackers can supply a single-column quoted CSV with no delimiters, triggering repeated full-buffer indexOf scans per row that grow quadratically with input size, exhausting CPU and blocking the Node.js event loop or freezing a browser tab.
Who should check
Teams running PapaParse before 5.7.1 in Node.js services or browser apps that parse untrusted quoted CSV with Papa.parse()
Read the source excerpt
“PapaParse before 5.7.1 contains an inefficient algorithmic complexity vulnerability”
cve.now Index
- Exploitation0/40No signal
- Exposure20/25No login or user action needed, CISA rates it automatable · Unknown: Advisories don't say whether default setups are affected
- Reach?/20Unknown. No tracked technology or package matched
- Severity8.7/10CVSS 8.7
- No patch0/5No signal
What would change the score
- Would score about 74 if added to CISA KEV
- Would score about 69 if CISA's SSVC rates exploitation active
- Would score about 34 if advisories confirm default setups are exposed
What to do
Upgrade to a fixed version: 5.7.1.
Check your systems with an agent
Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.
Check whether my systems are affected by CVE-2026-127056 (PapaParse before 5.7.1 Quadratic-Time Parsing DoS via indexOf Scan), using the cve.now data below.
Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.
What cve.now has for CVE-2026-127056 (entry last updated 2026-11-13):
Affected:
- mholt PapaParse: fixed in 5.7.1
Fixed versions: 5.7.1.
Conditions (all must be true for the bug to be hit):
- PapaParse version before 5.7.1 (source: https://www.vulncheck.com/advisories/papaparse-before-quadratic-time-parsing-dos-via-indexof-scan)
- Input is delimiter-free quoted CSV passed to Papa.parse() (source: https://www.vulncheck.com/advisories/papaparse-before-quadratic-time-parsing-dos-via-indexof-scan)
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
Attacker needs: network access, no login, no user action.
CISA KEV: CVE-2026-127056 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-127056 only. If you also check another CVE, look up its own KEV status; never assume it from this one.
How to check:
- Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory.
Verify against the linked advisories before concluding, and cite the date you read each one:
- https://www.npmjs.com/package/papaparse
- https://github.com/mholt/PapaParse/commit/a50fe19aae08b966de444119333fe4a8b7aa6b2f
- https://www.vulncheck.com/advisories/papaparse-before-quadratic-time-parsing-dos-via-indexof-scan
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.
Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.
Entry: https://cve.now/CVE-2026-127056
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-127056"}.Timeline
- CVE published
- First seen by cve.now1 day
- CISA SSVC assessment
Exploitation: none · Automatable: yes · Technical impact: partial
- Record last updated
Affected versions
- mholt PapaParse
fixed in 5.7.1
Evidence 5
CVE record · 2
Establishes: The identifier and description.
- Record
- Record
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-127056
Is CVE-2026-127056 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
Parsing a single-column quoted CSV with no delimiters through Papa.parse() takes excessive CPU time because of an inefficient algorithm. This can block the Node.js event loop or freeze a browser tab, which is a denial of service.Source: vulncheck.com
Which versions are affected by CVE-2026-127056?
PapaParse: before 5.7.1.Source: cve.now feed data
Am I affected, and how do I check?
PapaParse versions before 5.7.1 are affected when Papa.parse() is given delimiter-free quoted CSV input. To check the installed version, run npm ls papaparse in the project or look at the version field in node_modules/papaparse/package.json.Source: vulncheck.com
How do I fix CVE-2026-127056?
Upgrade PapaParse to 5.7.1 or later, the fixed version listed for this vulnerability.Source: vulncheck.com