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Fencer Intel
critical 9.8

CVE-2021-24036 json

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

published 5y ago modified 4mo ago also EUVD-2021-10955

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
3.3%
EPSS 3.3% chance of exploitation in 30 days, percentile 88%
public exploits
0
none known

Summary

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.

Patch / fix

  • Facebook folly v2021.07.22.00
  • Facebook HHVM 4.80.5

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Exploit prediction

3.28% chance of exploitation in the next 30 days, higher than 88% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P

Affected products

  • Facebook folly
  • Facebook HHVM

Classification

Weakness
  • CWE-122 Heap-based Buffer Overflow
  • CWE-190 Integer Overflow or Wraparound

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.