5.9

CVE-2021-23841: Null pointer deref in X509_issuer_and_serial_hash()

Modified
AliasesALPINE-CVE-2021-23841UBUNTU-CVE-2021-23841DEBIAN-CVE-2021-23841
Published 16-02-2021Last modified 16-09-2024

Vulnerability summary

CVE-2021-23841 is a medium (CVSS 5.9) NULL Pointer Dereference vulnerability in apple ipados. EPSS estimates a 7.41% chance of exploitation in the next 30 days, higher than 94.4% of scored vulnerabilities.

Priority
Routine

Not severe (CVSS 5.9, network access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
5.9/10
010
Medium · v3.1 (NVD)
EPSS score
7.41%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 25 · Related 16
DLA-2563-1DLA-2565-1DSA-4855-1MGASA-2021-0108OPENSUSE-SU-2021:0427-1OPENSUSE-SU-2021:0430-1

Timeline

  1. 16-02-2021
    PublishedVulnerability first disclosed.
  2. 16-09-2024
    Last modifiedVulnerability information updated.

Description

The OpenSSL public API function X509_issuer_and_serial_hash() attempts to create a unique hash value based on the issuer and serial number data contained within an X509 certificate. However it fails to correctly handle any errors that may occur while parsing the issuer field (which might occur if the issuer field is maliciously constructed). This may subsequently result in a NULL pointer deref and a crash leading to a potential denial of service attack. The function X509_issuer_and_serial_hash() is never directly called by OpenSSL itself so applications are only vulnerable if they use this function directly and they use it on certificates that may have been obtained from untrusted sources. OpenSSL versions 1.1.1i and below are affected by this issue. Users of these versions should upgrade to OpenSSL 1.1.1j. OpenSSL versions 1.0.2x and below are affected by this issue. However OpenSSL 1.0.2 is out of support and no longer receiving public updates. Premium support customers of OpenSSL 1.0.2 should upgrade to 1.0.2y. Other users should upgrade to 1.1.1j. Fixed in OpenSSL 1.1.1j (Affected 1.1.1-1.1.1i). Fixed in OpenSSL 1.0.2y (Affected 1.0.2-1.0.2x).

CVSS metrics

6 scores · 5 sources · 2 versions

EPSS trend

Probability

7.41%

Chance of exploitation in the next 30 days

Percentile

94%

Versus all other CVEs

30-day change

No change 0.00 pp

From 7.41% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.

Oracle11 products
Apple4 products
Alpine3 products
  • openssl≥ 1.0.2, < 1.1.1j-r0
  • openssl1.1-compat< 1.1.1j-r0
  • openssl3< 1.1.1j-r0
Netapp3 products
Debian2 products
Tenable2 products
Ubuntu2 products
  • openssl< 1.0.1f-1ubuntu2.27+esm2 | < 1.0.2g-1ubuntu4.19 | < 1.1.1-1ubuntu2.1~18.04.8 | < 1.1.1f-1ubuntu2.2
  • openssl1.0< 1.0.2n-1ubuntu5.6
Crates.Io1 product
  • openssl-src< 111.14.0 | ≥ 0.0.0-0, < 111.14.0
Openssl1 product
  • opensslFixed in OpenSSL 1.1.1j (Affected 1.1.1-1.1.1i) | Fixed in OpenSSL 1.0.2y (Affected 1.0.2-1.0.2x) | ≥ 1.0.2, < 1.0.2y | ≥ 1.1.1, < 1.1.1j
Siemens1 product

10 vendors · 30 products

References

39 links
Show all 39 references