Skip to content
Noroxi
NVD / CVE Program· CNA facebook

CVE-2021-24036: Passing an attacker controlled size when creating an IOBuf could cause integer overflow, leading to an out of bounds write on the heap with…

CriticalCVSS 9.8 · v3.1—No exploit No fix recorded

Noroxi assessment

Priority: Plan (action score 40/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 3.2% (FIRST EPSS); higher than 88.6% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • No fixed version is recorded, but the references include a patch (commit or PR) link.

Add it to your regular patch cycle. See the fix and affected versions sections below.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

Passing an attacker controlled size when creating an IOBuf could cause integer overflow, leading to an out of bounds write on the heap with the possibility of remote code execution. This issue affects versions of folly prior to v2021.07.22.00. This issue affects HHVM versions prior to 4.80.5, all versions between 4.81.0 and 4.102.1, all versions between 4.103.0 and 4.113.0, and versions 4.114.0, 4.115.0, 4.116.0, 4.117.0, 4.118.0 and 4.118.1.

Published
Jul 22, 2021
Updated
Jun 16, 2026
EPSS
3.2% · 88th percentile

Report tools

JSON

Action score

40

Plan

Add it to your regular patch cycle.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
1 / 30 · 3.2%

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • No fixed version yet

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2021-24036

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

One daily email digest (06:00 UTC); connect a webhook for KEV listings and weaponized exploits every 10 minutes on paid plans, on the hour on the free plan.

Your free account also gets you

  • CVE alerts: add the products and versions you run, get the new CVEs that affect them
  • Uptime monitoring: 1 site, instant email when it goes down
  • Add your domain: subdomains and takeover risk scanned every week (1 domain)
  • 10 scans an hour on the security tools, at most 30 a day (3 a day without an account), an API key and MCP
  • All your scans in one panel: findings, what changed in the last scan, a report per domain or per client (PDF, share link)
All free tools

Sign up with email · Have an account? Sign in

Free account, no card. Unfollow any time.

Don't want an account? Get "Exploited this week" by email every MondayDon't want an account? RSS feed for facebook records
Is your version affected? Check it

Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

We use this product, ask for help

Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
facebookfolly
facebookhhvm

Versions reported by the vendor

Affected version ranges reported by the assigning authority (facebook). Independent of NVD's CPE analysis and usually ahead of it.

  • Facebook folly

    • v2021.07.22.00 and later · before unspecifiednot affected
    • unspecified and later · before v2021.07.22.00affected

  • Facebook HHVM

    • 4.117.0, 4.116.0, 4.115.0, 4.114.0, 4.113.0affected
    • 4.118.2 and later · before unspecifiednot affected
    • 4.118.0 and later · before unspecifiedaffected
    • 4.117.1 and later · before unspecifiednot affected
    • 4.116.1 and later · before unspecifiednot affected
    • 4.115.1 and later · before unspecifiednot affected
    • 4.114.1 and later · before unspecifiednot affected
    • 4.113.1 and later · before unspecifiednot affected
    • 4.102.2 and later · before unspecifiednot affected
    • 4.102.0 and later · before unspecifiedaffected
Affected versions · NVD (10)

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • facebook follybefore 2021.07.22.00
  • facebook hhvmbefore 4.80.5
  • facebook hhvm4.81.0 and later · up to 4.102.1 inclusive
  • facebook hhvm4.103.0 and later · up to 4.113.0 inclusive
  • facebook hhvm4.114.0
  • facebook hhvm4.115.0
  • facebook hhvm4.116.0
  • facebook hhvm4.117.0
  • facebook hhvm4.118.0
  • facebook hhvm4.118.1

Same product

facebook: all records

Other highest-scoring records for the same primary product.

  • CVE-2019-11934Improper handling of close_notify alerts can result in an out-of-bounds read in AsyncSSLSocket.
    40Plan
  • CVE-2018-6337folly::secureRandom will re-use a buffer between parent and child processes when fork() is called.
    31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Not on record for this CVE: EPSS history · researcher credit · variant or chain candidate · public bounty program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-122 · Heap-based Buffer Overflow

CVSS vector

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

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

References

Show all references (2 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records