Security Bulletin
Summary
IBM Optim for z/OS version 1.0.0, 1.1.0 and 1.2.0 depends on open-source packages jackc/Pgx, cloudflare/cfSSL and x/net which are affected by medium, high and critical severity vulnerabilities. IBM Optim for z/OS 2.0.0 resolves these vulnerabilities by upgrading the affected open-source dependencies to a version with the vulnerabilities addressed..
Vulnerability Details
CVEID: CVE-2026-33814
DESCRIPTION: When processing HTTP/2 SETTINGS frames, transport will enter an infinite loop of writing CONTINUATION frames if it receives a SETTINGS_MAX_FRAME_SIZE with a value of 0.
CWE: CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop')
CVSS Source: NVD
CVSS Base score: 7.5
CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
CVEID: CVE-2026-33815
DESCRIPTION: Memory-safety vulnerability in github.com/jackc/pgx/v5.
CWE: CWE-787: Out-of-bounds Write
CVSS Source: CISA ADP
CVSS Base score: 9.8
CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)
CVEID: CVE-2026-33816
DESCRIPTION: Memory-safety vulnerability in github.com/jackc/pgx/v5.
CWE: CWE-787: Out-of-bounds Write
CVSS Source: CISA ADP
CVSS Base score: 9.8
CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)
CVEID: CVE-2021-34558
DESCRIPTION: The crypto/tls package of Go through 1.16.5 does not properly assert that the type of public key in an X.509 certificate matches the expected type when doing a RSA based key exchange, allowing a malicious TLS server to cause a TLS client to panic.
CWE: CWE-295: Improper Certificate Validation
CVSS Source: IBM X-Force
CVSS Base score: 6.5
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H)
CVEID: CVE-2022-41724
DESCRIPTION: Large handshake records may cause panics in crypto/tls. Both clients and servers may send large TLS handshake records which cause servers and clients, respectively, to panic when attempting to construct responses. This affects all TLS 1.3 clients, TLS 1.2 clients which explicitly enable session resumption (by setting Config.ClientSessionCache to a non-nil value), and TLS 1.3 servers which request client certificates (by setting Config.ClientAuth = RequestClientCert).
CWE: CWE-400: Uncontrolled Resource Consumption
CVSS Source: IBM X-Force
CVSS Base score: 6.5
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
CVEID: CVE-2023-29409
DESCRIPTION: Extremely large RSA keys in certificate chains can cause a client/server to expend significant CPU time verifying signatures. With fix, the size of RSA keys transmitted during handshakes is restricted to = 8192 bits. Based on a survey of publicly trusted RSA keys, there are currently only three certificates in circulation with keys larger than this, and all three appear to be test certificates that are not actively deployed. It is possible there are larger keys in use in private PKIs, but we target the web PKI, so causing breakage here in the interests of increasing the default safety of users of crypto/tls seems reasonable.
CWE: CWE-400: Uncontrolled Resource Consumption
CVSS Source: IBM X-Force
CVSS Base score: 5.7
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H)
CVEID: CVE-2026-41889
DESCRIPTION: pgx is a PostgreSQL driver and toolkit for Go. Prior to version 5.9.2, SQL injection can occur when the non-default simple protocol is used, a dollar quoted string literal is used in the SQL query, that string literal contains text that would be would be interpreted as a placeholder outside of a string literal, and the value of that placeholder is controllable by the attacker. This issue has been patched in version 5.9.2.
CWE: CWE-89: Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection')
CVSS Source: NVD
CVSS Base score: 9.8
CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)
Affected Products and Versions
| Affected Product(s) | Version(s) |
| IBM Optim for z/OS | 1.0.0 |
| IBM Optim for z/OS | 1.1.0 |
| IBM Optim for z/OS | 1.2.0 |
Remediation/Fixes
IBM strongly recommends addressing the vulnerability now.
Move to IBM Optim for z/OS 2.0.0.
IBM Optim for z/OS 2.0.0 addresses these vulnerabilities.
jackc/Pgx has been upgraded from 5.5.5 to 5.9.2 which fixes the vulnerability (CVE-2026-41889, CVE-2026-33815, CVE-2026-33816)
cloudflare/cfSSL has been removed, fixing the vulnerabilities (CVE-2021-34558, CVE-2022-41724, CVE-2023-29409)
x/net has been upgraded from 0.41.0 to 0.54.0 which fixes the vulnerabilities (CVE-2026-33814)
Available from https://www.ibm.com/software/passportadvantage/pao-customer
Workarounds and Mitigations
None
Get Notified about Future Security Bulletins
References
Acknowledgement
Change History
28 Sep 2026: Initial Publication
*The CVSS Environment Score is customer environment specific and will ultimately impact the Overall CVSS Score. Customers can evaluate the impact of this vulnerability in their environments by accessing the links in the Reference section of this Security Bulletin.
Disclaimer
According to the Forum of Incident Response and Security Teams (FIRST), the Common Vulnerability Scoring System (CVSS) is an "industry open standard designed to convey vulnerability severity and help to determine urgency and priority of response." IBM PROVIDES THE CVSS SCORES ""AS IS"" WITHOUT WARRANTY OF ANY KIND, INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. CUSTOMERS ARE RESPONSIBLE FOR ASSESSING THE IMPACT OF ANY ACTUAL OR POTENTIAL SECURITY VULNERABILITY. In addition to other efforts to address potential vulnerabilities, IBM periodically updates the record of components contained in our product offerings. As part of that effort, if IBM identifies previously unidentified packages in a product/service inventory, we address relevant vulnerabilities regardless of CVE date. Inclusion of an older CVEID does not demonstrate that the referenced product has been used by IBM since that date, nor that IBM was aware of a vulnerability as of that date. We are making clients aware of relevant vulnerabilities as we become aware of them. "Affected Products and Versions" referenced in IBM Security Bulletins are intended to be only products and versions that are supported by IBM and have not passed their end-of-support or warranty date. Thus, failure to reference unsupported or extended-support products and versions in this Security Bulletin does not constitute a determination by IBM that they are unaffected by the vulnerability. Reference to one or more unsupported versions in this Security Bulletin shall not create an obligation for IBM to provide fixes for any unsupported or extended-support products or versions.
Document Location
Worldwide
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Document Information
Modified date:
28 September 2026
Initial Publish date:
28 September 2026
UID
ibm17289721