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Fencer Vulns
high 7.5

CVE-2021-4044 in the critical feed json

Invalid handling of X509_verify_cert() internal errors in libssl

published 2021-12-14 4 y ago modified 2026-09-08 2 mo ago also BIT-node-2021-4044 , BIT-node-min-2021-4044 , EUVD-2021-2556 , GHSA-mmjf-f5jw-w72q , RUSTSEC-2021-0129

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
50.1%
EPSS 50.1% chance of exploitation in 30 days, percentile 98%
public exploits
0
none known

Summary

Internally libssl in OpenSSL calls X509_verify_cert() on the client side to verify a certificate supplied by a server. That function may return a negative return value to indicate an internal error (for example out of memory). Such a negative return value is mishandled by OpenSSL and will cause an IO function (such as SSL_connect() or SSL_do_handshake()) to not indicate success and a subsequent call to SSL_get_error() to return the value SSL_ERROR_WANT_RETRY_VERIFY. This return value is only supposed to be returned by OpenSSL if the application has previously called SSL_CTX_set_cert_verify_callback(). Since most applications do not do this the SSL_ERROR_WANT_RETRY_VERIFY return value from SSL_get_error() will be totally unexpected and applications may not behave correctly as a result. The exact behaviour will depend on the application but it could result in crashes, infinite loops or other similar incorrect responses. This issue is made more serious in combination with a separate bug in OpenSSL 3.0 that will cause X509_verify_cert() to indicate an internal error when processing a certificate chain. This will occur where a certificate does not include the Subject Alternative Name extension but where a Certificate Authority has enforced name constraints. This issue can occur even with valid chains. By combining the two issues an attacker could induce incorrect, application dependent behaviour. Fixed in OpenSSL 3.0.1 (Affected 3.0.0).

Patch / fix

  • crates.io openssl-src 300.0.4
  • bitnami node 17.3.0
  • bitnami node-min 17.3.0
  • openssl openssl 1.0.2
  • nodejs node.js 17.3.0
  • openssl Ubuntu 22.04 LTS 3.0.1-0ubuntu1

ubuntu advisories UBUNTU-CVE-2021-4044

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • openssl-3 openSUSE Tumbleweed 3.0.1-1.1

opensuse advisories openSUSE-SU-2024:11797-1

  • openssl Alpine 3.24, Alpine 3.23, Alpine 3.22 +5 more 3.0.1-r0
  • openssl3 Alpine 3.15 3.0.2-r0
  • openssl3 Alpine 3.16 3.0.1-r0

alpine advisories ALPINE-CVE-2021-4044

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-4044 updated cvss 7.5

openssl: invalid handling of X509_verify_cert() internal errors in libssl

  • Red Hat Advanced Cluster Management for Kubernetes 2 rhacm2/management-ingress-rhel8 Red Hat Enterprise Linux 6 openssl, openssl098e, openssl-perl Red Hat Enterprise Linux 7 openssl, openssl098e, openssl-libs, openssl-perl Red Hat Enterprise Linux 8 openssl, openssl-libs, openssl-perl, compat-openssl10 Red Hat Enterprise Linux 9 openssl, openssl-libs, openssl-perl Red Hat JBoss Core Services jbcs-httpd24-openssl
    +2 more products
    Red Hat JBoss Web Server 3 openssl Red Hat JBoss Web Server 5 openssl
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

50.10% chance of exploitation in the next 30 days, higher than 98% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P
OSV 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
crates.io openssl-src
>=300.0.0, <300.0.4
300.0.4
bitnami node
>=17.0.0, <17.3.0
17.3.0
bitnami node-min
>=17.0.0, <17.3.0
17.3.0

Affected products

  • OpenSSL OpenSSL

Classification

Weakness
  • CWE-835 Loop with Unreachable Exit Condition
Technology feeds

References

Sources

Fencer Vulns 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.