glibc: Reachable Assertion
CVE-2026-4046 is a high-severity reachable assertion vulnerability in glibc from The GNU C Library, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected glibc versions: 2.3.3 through 2.43. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.39% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update SIMATIC S7-1500 CPU 1518-4 PN/DP MFP to V3.1.6 or a later version.
- Update SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP to V3.1.6 or a later version.
- Update SIPLUS S7-1500 CPU 1518-4 PN/DP MFP to V3.1.6 or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| The GNU C Library | glibc | 2.3.3 through 2.43 | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP | V3.1.5 up to, but not including, V3.1.6 | V3.1.6 |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP | V3.1.5 up to, but not including, V3.1.6 | V3.1.6 |
| Siemens | SIPLUS S7-1500 CPU 1518-4 PN/DP MFP | V3.1.5 up to, but not including, V3.1.6 | V3.1.6 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by CISA (ADP).
Official description
The iconv() function in the GNU C Library versions 2.43 and earlier may crash due to an assertion failure when converting inputs from the IBM1390 or IBM1399 character sets, which may be used to remotely crash an application. This vulnerability can be trivially mitigated by removing the IBM1390 and IBM1399 character sets from systems that do not need them.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Reachable Assertion
The product contains an assert() or similar statement that can be triggered by an attacker, which leads to an application exit or other behavior that is more severe than necessary.
How developers prevent this class of flaw
- If the assertion statement is required (e.g., for security or reliability), change the invoking code to avoid the conditions that trigger the assertion.
- Consider changing the assertion to some other less fatal error. This might not be easy to implement, since other code may be needed to handle the error.
- Make sensitive open/close operations non-reachable from directly user-controlled data (e.g. open/close resources)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- sourceware.org/bugzilla/show_bug.cgi?id=33980Exploit, Issue Tracking
Third-party and government advisories
Other references
Other vulnerabilities in glibc
- 7.0 High severity
- 7.7 High severity
- 7.3 High severity
- 7.5 High severity
- 9.8 Critical severity
- 7.5 High severity
Recent Reachable Assertion vulnerabilities
- 7.5 High severity
- 7.1 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
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