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Fencer Intel
medium 5.4

CVE-2021-38997 json

IBM API Connect HOST header injection

published 3y ago modified 4mo ago also EUVD-2021-25434

cvss
5.4
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 37%
public exploits
0
none known

Summary

IBM API Connect V10.0.0.0 through V10.0.5.0, V10.0.1.0 through V10.0.1.7, and V2018.4.1.0 through 2018.4.1.19 is vulnerable to HTTP header injection, caused by improper validation of input by the HOST headers. This could allow an attacker to conduct various attacks against the vulnerable system, including cross-site scripting, cache poisoning or session hijacking. IBM X-Force ID: 213212.

Patch / fix

  • IBM API Connect 10.0.1.7, 10.0.5.0, 2018.4.1.19

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CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
last yr.

Exploit prediction

0.43% chance of exploitation in the next 30 days, higher than 37% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
NVD 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

Affected products

  • IBM API Connect

Classification

Weakness
  • CWE-644 Improper Neutralization of HTTP Headers for Scripting Syntax
  • CWE-116 Improper Encoding or Escaping of Output

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.