CVE-2021-23841

mediumpriority · track · 37OT risk · elevatedEPSS 0.074 · 94 %ileexploit · PoCDEEURUUS
grimoire priorityP1 · Urgent
Exploitable?
Public exploit
2 exploits · PoC
Likely / severe?
7.41% (94th) EPSS
CVSS 4.3 · medium
Is it mine?
64 products
Check your exposure
Who says so?
7 sources
cnnvd · enisa_euvd · fstec_bdu · osv

EPSS · scored 2026-10-26

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).

01

remediations

Vendor fix, mitigation, or workaround guidance, as published by each source.

A vendor fix is available.

02

cvss

Technical severity, 0–10. One row per scoring source.

5.9
010

base score 0–10 · higher = more severe · hover a vector to decode

v2.04.3mediumAV:N/AC:M/Au:N/C:N/I:N/A:Pprimary · NVD / NIST USexploitability 8.6 · impact 2.9
v3.15.9mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:Hprimary · NVD / NIST USexploitability 2.2 · impact 3.6
v3.05.9mediumCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondary · CISA US
v3.15.9mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondary · OSV
v3.15.9mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H/E:P/RL:O/RC:Csecondary · Siemens ProductCERT DE
v3.15.6mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H/E:Psecondary · CVSS-BT (t0sche)
v3.15.9mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H/E:P/RL:O/RC:Csecondary · CISA US
v3.15.9mediumAV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondary · FSTEC (BDU) RU
03

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Trackcoordinatorcisa_ssvcUS
04

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-476USprimaryCWE-190USCWE-190USCWE-311USCWE-311USCWE-476USCWE-476US
05

exploits (2)

Public proof-of-concept and weaponised exploit code.

06

affected products (64)

Products and version ranges known to be affected.

showing 20 of 64
07

advisories (12)

Vendor and ecosystem advisories describing this.

  • SSA-637483SSA-637483 Third-Party Component Vulnerabilities in SINEC INS before V1.0 SP22022-09-13csaf · siemens_psirtDE

    Multiple vulnerabilities affecting various third-party components of SINEC INS before V1.0 SP2 could allow an attacker to cause a denial of service condition, disclose sensitive data or violate the system integrity. Siemens has released an update for the SINEC INS and recommends to update to the latest version.

  • WID-SEC-W-2022-0602IBM Security Verify Access: Mehrere SchwachstellenDeutsch2022-07-06csaf · cert_bundDE

    Ein entfernter anonymer, authentisierter oder lokaler Angreifer oder ein Angreifer aus dem angrenzenden Netzwerk kann mehrere Schwachstellen in IBM Security Verify Access ausnutzen, um einen Cross-Site-Scripting-Angriff durchzuführen, vertrauliche Informationen offenzulegen, seine Privilegien zu erweitern, Informationen zu manipulieren, einen Denial-of-Service-Zustand zu verursachen und Sicherheitsmaßnahmen zu umgehen.

  • WID-SEC-W-2022-0669OpenSSL: Mehrere SchwachstellenDeutsch2021-02-16csaf · cert_bundDE

    Ein entfernter, anonymer oder lokaler Angreifer kann mehrere Schwachstellen in OpenSSL ausnutzen, um Sicherheitsvorkehrungen zu umgehen oder einen Denial of Service Zustand herzustellen.

  • WID-SEC-W-2022-0676Juniper Junos Space: Mehrere SchwachstellenDeutsch2022-07-13csaf · cert_bundDE

    Ein entfernter, anonymer, authentisierter oder lokaler Angreifer kann mehrere Schwachstellen in Juniper Junos Space ausnutzen, um einen Denial-of-Service-Zustand herbeizuführen, vertrauliche Informationen offenzulegen, Daten zu manipulieren oder zu verändern, seine Privilegien zu erweitern und Sicherheitsmaßnahmen zu umgehen.

  • WID-SEC-W-2022-1303Oracle Java SE: Mehrere SchwachstellenDeutsch2021-04-20csaf · cert_bundDE

    Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in Oracle Java SE und Oracle GraalVM ausnutzen, um die Verfügbarkeit, Vertraulichkeit und Integrität zu gefährden.

  • WID-SEC-W-2023-0065Oracle MySQL: Mehrere SchwachstellenDeutsch2021-04-20csaf · cert_bundDE

    Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in Oracle MySQL ausnutzen, um die Verfügbarkeit, Vertraulichkeit und Integrität zu gefährden.

  • WID-SEC-W-2024-0794Dell ECS: Mehrere SchwachstellenDeutsch2024-04-04csaf · cert_bundDE

    Ein Angreifer kann mehrere Schwachstellen in Dell ECS ausnutzen, um seine Privilegien zu erweitern, beliebigen Programmcode mit Administratorrechten auszuführen, Informationen offenzulegen, Dateien zu manipulieren, einen Cross-Site-Scripting-Angriff durchzuführen, Sicherheitsvorkehrungen zu umgehen oder einen Denial of Service Zustand herbeizuführen.

  • WID-SEC-W-2026-0180Dell Data Protection Advisor: Mehrere SchwachstellenDeutsch2026-01-20csaf · cert_bundDE

    Ein Angreifer kann mehrere Schwachstellen in Dell Data Protection Advisor ausnutzen, um beliebigen Code auszuführen, einen Denial-of-Service-Zustand zu erzeugen, Sicherheitsmaßnahmen zu umgehen und nicht näher spezifizierte Angriffe zu starten.

  • GHSA-84rm-qf37-fgc2Integer Overflow in openssl-src2021-08-25ghsa · osvUS

    Calls to EVP_CipherUpdate, EVP_EncryptUpdate and EVP_DecryptUpdate may overflow the output length argument in some cases where the input length is close to the maximum permissable length for an integer on the platform. In such cases the return value from the function call will be 1 (indicating success), but the output length value will be negative. This could cause applications to behave incorrectly or crash. 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).

  • ICSA-21-336-06Hitachi Energy APM Edge2021-12-02icsa · cisa_csaf_otUS

    Successful exploitation of this vulnerability could cause the product to become inaccessible.

  • ICSA-22-258-05Siemens SINEC INS2022-09-13icsa · cisa_csaf_otUS

    Multiple vulnerabilities affecting various third-party components of SINEC INS before V1.0 SP2 could allow an attacker to cause a denial of service condition, disclose sensitive data or violate the system integrity. Siemens has released an update for the SINEC INS and recommends to update to the latest version.

  • RUSTSEC-2021-0058Null pointer deref in `X509_issuer_and_serial_hash()`2021-05-01vendor · osvUS

    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.

08

also known as (7)

Other names and identifiers for this entity.

09

sources

Which sources assert this record, and when.

cnnvdenisa_euvdfstec_bduosvcert_bundcisa_csaf_otsiemens_psirtNVDCVE.orgMITRE
published 2021-02-16modified 2026-06-17
11

references (160)

External citations — patches, advisories, analysis.

scry

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