CVE-2026-43513VulnerabilityPublished 23 Jul 2026Updated 5 Nov 2026

Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update

Affects Red HatSource GCVE Database

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Authoritative record:CVE-2026-43513· High 7.5

Not known to be exploited · CVSS 7.5 High : upgrade Red Hat tomcat to 8.5.101 or 7.0.110 soon.

Data as of 6 Nov 2026, 02:21 UTC

CVSS 3.1 base score

7.5High

How severe the flaw is on the 0–10 CVSS scale.

Patch: Available – fixed in 8.5.101, 7.0.110

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 12 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 5 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade org.apache.tomcat/tomcat to 8.5.101 or 7.0.110.

Affected software

Product	Affected	Fixed in
Apache Software FoundationApache Tomcat	Affected >=11.0.0-M1 <=11.0.21 >=10.1.0-M1 <=10.1.54 >=9.0.0.M1 <=9.0.117 >=8.5.0 <=8.5.100 >=7.0.0 <=7.0.109	Fixed in–
Mavenorg.apache.tomcat/tomcat`pkg:maven/org.apache.tomcat/tomcat`Other threats	Affected =8.5.0 <8.5.101 =7.0.0 <7.0.110	Fixed in 8.5.101 7.0.110

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Red Hat has released updated tomcat11 RPM packages as part of the Hardened Images update to address this vulnerability. Users should apply these updates to mitigate the issue. The vulnerability only affects configurations using LockOutRealm with case-insensitive authentication backends; if this configuration is not in use, no action is required. For affected deployments, upgrading to the updated tomcat11 packages is the recommended remediation.

Description

A vulnerability in Apache Tomcat's LockOutRealm component mishandles case sensitivity in usernames when configured with a case-insensitive authentication backend. This flaw reduces the effectiveness of brute-force attack protections by not properly accounting for case differences in usernames. The issue affects only non-default configurations where LockOutRealm is used with case-insensitive realms. Red Hat has issued an update for Red Hat Hardened Images RPMs including tomcat11 packages to address this issue.

Impact

The vulnerability reduces the effectiveness of brute-force attack protections in Apache Tomcat deployments using LockOutRealm with case-insensitive authentication backends. Attackers may exploit case variations in usernames to bypass account lockout mechanisms, increasing the risk of unauthorized access. Deployments not using LockOutRealm or using case-sensitive authentication backends are not affected. There are no reported exploits in the wild.

Summary

CVE-2026-43513 describes a security flaw in Apache Tomcat's LockOutRealm where case sensitivity in usernames is improperly handled. Specifically, when LockOutRealm is configured with an underlying Realm that treats usernames as case-insensitive, the LockOutRealm does not normalize case, potentially allowing attackers to bypass brute-force protections by exploiting case variations in usernames. This vulnerability requires the LockOutRealm to be configured with a case-insensitive authentication backend, which is not the default setting. Red Hat released an update to tomcat11 RPMs in their Hardened Images to fix this issue. The vulnerability is classified under CWE-178 (Improper Handling of Case Sensitivity) and has a medium severity rating by Red Hat with a CVSS v3 base score of 5.3.

CWE-178Improper Handling of Case Sensitivity (opens in a new tab)
Base weakness
The product does not properly account for differences in case sensitivity when accessing or determining the properties of a resource, leading to inconsistent results.
Architecture and Design · Input Validation
Avoid making decisions based on names of resources (e.g. files) if those resources can have alternate names.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
Implementation · Input Validation
Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174).
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 6 Nov 2026, 02:21 UTC

WeaknessesCWE-178

Technical details

References

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