CVE-2021-23841
What it is
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).
At a glance
- Exploitability
- Can be exploited over the network without logging in. High risk of service disruption.
- Exploit odds
- 7.4% chance of exploitation in the next 30 days (EPSS).
- Fix
- A patch, advisory or fixed version is referenced. Upgrade or apply it.
Timeline
- PublishedDisclosed publicly on CVE.org and NVD
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: no, CISA does not list it.
- Exploit odds: 7.4% in the next 30 days (EPSS).
- Severity: 5.9 MEDIUM (CVSS).
- Fix: a patch or advisory is linked.
Details
- Published
- Last modified
- Exploit probability
- 7.4% · EPSS, next 30 days
- Weakness
- CWE-476 · NULL pointer dereference
- Record status
- Modified
Affected
- OpenSSL < 1.0.2y
- OpenSSL < 1.1.1j
- Debian Linux 10.0
- Tenable Nessus Network Monitor 5.11.0
- Tenable Nessus Network Monitor 5.11.1
- Tenable Nessus Network Monitor 5.12.0
- Tenable Nessus Network Monitor 5.12.1
- Tenable Nessus Network Monitor 5.13.0
Attack profile CVSS 3.1 · 5.9
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Raw vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2021-23841.md and follow it. Check whether this project is affected by CVE-2021-23841. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
Fix and advisories
- https://cert-portal.siemens.com/productcert/pdf/ssa-637483.pdf
- https://www.openssl.org/news/secadv/20210216.txt
- https://www.oracle.com//security-alerts/cpujul2021.html
- https://www.oracle.com/security-alerts/cpuApr2021.html
- https://www.oracle.com/security-alerts/cpuapr2022.html
- https://www.oracle.com/security-alerts/cpuoct2021.html
- https://cert-portal.siemens.com/productcert/pdf/ssa-637483.pdf
- https://www.openssl.org/news/secadv/20210216.txt
- https://www.oracle.com//security-alerts/cpujul2021.html
- https://www.oracle.com/security-alerts/cpuApr2021.html
References
- http://seclists.org/fulldisclosure/2021/May/67
- http://seclists.org/fulldisclosure/2021/May/68
- http://seclists.org/fulldisclosure/2021/May/70
- https://cert-portal.siemens.com/productcert/pdf/ssa-637483.pdf
- https://git.openssl.org/gitweb/?p=openssl.git%3Ba=commitdiff%3Bh=122a19ab48091c657f7cb1fb3af9fc07bd557bbf
- https://git.openssl.org/gitweb/?p=openssl.git%3Ba=commitdiff%3Bh=8252ee4d90f3f2004d3d0aeeed003ad49c9a7807
- https://kb.pulsesecure.net/articles/Pulse_Security_Advisories/SA44846
- https://security.gentoo.org/glsa/202103-03
- https://security.netapp.com/advisory/ntap-20210219-0009/
- https://security.netapp.com/advisory/ntap-20210513-0002/
- https://security.netapp.com/advisory/ntap-20240621-0006/
- https://support.apple.com/kb/HT212528
- https://support.apple.com/kb/HT212529
- https://support.apple.com/kb/HT212534
- https://www.debian.org/security/2021/dsa-4855
- https://www.openssl.org/news/secadv/20210216.txt
- https://www.oracle.com//security-alerts/cpujul2021.html
- https://www.oracle.com/security-alerts/cpuApr2021.html
- https://www.oracle.com/security-alerts/cpuapr2022.html
- https://www.oracle.com/security-alerts/cpuoct2021.html
- https://www.tenable.com/security/tns-2021-03
- https://www.tenable.com/security/tns-2021-09
- http://seclists.org/fulldisclosure/2021/May/67
- http://seclists.org/fulldisclosure/2021/May/68
- http://seclists.org/fulldisclosure/2021/May/70