Red Hat Security Advisory: tomcat security update
Affects Red Hat tomcatSource GCVE Database
Mentioned vulnerabilities
Not known to be exploited · CVSS 7.6 High.
Data as of 5 Nov 2026, 20:35 UTC
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L- Attack Vector
- Network
- Attack Complexity
- Low
- Privileges Required
- Low
- User Interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- Low
- Availability
- Low
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: Low
- The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
- 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: Low
- Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
- Availability: Low
- Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.
Definitions: FIRST CVSS v3.1 specification.
Exploitation evidence
Disclosed: evidence found.
CVE published 17 Feb 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
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Apache Software FoundationApache Tomcat | Affected
| Fixed in– |
AI-suggested
Red Hat has released updated Tomcat packages (version 9.0.117-1.el9_8) for Red Hat Enterprise Linux 9 and related variants that fix this vulnerability. Users should apply these updates promptly following Red Hat's guidance at https://access.redhat.com/articles/11258. No additional mitigation steps are indicated or required beyond applying the official update.
Description
A security update for Apache Tomcat addresses a certificate revocation bypass vulnerability caused by improper OCSP response validation (CVE-2026-24734). This issue affects Red Hat Enterprise Linux 9 and related variants. The vulnerability could allow bypassing certificate revocation checks, potentially impacting secure communications. Red Hat has released updated Tomcat packages to fix this issue.
Impact
Improper validation of OCSP responses in Apache Tomcat could allow an attacker to bypass certificate revocation checks, potentially enabling the use of revoked certificates in secure communications. This undermines the trust model of TLS connections relying on OCSP for revocation status, possibly leading to man-in-the-middle or other attacks that rely on revoked certificates being accepted as valid.
Summary
The advisory covers a security fix for Apache Tomcat, specifically addressing CVE-2026-24734, which involves a certificate revocation bypass due to improper validation of OCSP responses. This vulnerability affects Red Hat Enterprise Linux 9 and its extended update support and lifecycle variants across multiple architectures (x86_64, s390x, ppc64le, aarch64). The update to Tomcat version 9.0.117-1.el9_8 resolves this issue. The advisory references multiple CVEs but highlights CVE-2026-24734 as the primary security fix. No CVSS score is provided in the advisory, but Red Hat rates the update as Important.
- CWE-1289Improper Validation of Unsafe Equivalence in Input (opens in a new tab)
Base weakness
The product receives an input value that is used as a resource identifier or other type of reference, but it does not validate or incorrectly validates that the input is equivalent to a potentially-unsafe value.
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.
- OWASP Cheat Sheets
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
- CWE-20Improper Input Validation (opens in a new tab)
Class weaknessLikelihood of exploit: HighCWE Top 25 (2025): #18OWASP Top 10 A05:2025: Injection (opens in a new tab)
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
Architecture and Design · Attack Surface Reduction
Consider using language-theoretic security (LangSec) techniques that characterize inputs using a formal language and build "recognizers" for that language. This effectively requires parsing to be a distinct layer that effectively enforces a boundary between raw input and internal data representations, instead of…
Architecture and Design · Libraries or Frameworks
Use an input validation framework such as Struts or the OWASP ESAPI Validation API. Note that using a framework does not automatically address all input validation problems; be mindful of weaknesses that could arise from misusing the framework itself (CWE-1173).
Architecture and Design · Implementation · Attack Surface Reduction
Understand all the potential areas where untrusted inputs can enter the product, including but not limited to: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any…
- OWASP Cheat Sheets
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
- CWE-295Improper Certificate Validation (opens in a new tab)
Base weaknessOWASP Top 10 A07:2025: Authentication Failures (opens in a new tab)
The product does not validate, or incorrectly validates, a certificate.
Architecture and Design · Implementation
Certificates should be carefully managed and checked to assure that data are encrypted with the intended owner's public key.
Implementation
If certificate pinning is being used, ensure that all relevant properties of the certificate are fully validated before the certificate is pinned, including the hostname.
- OWASP Cheat Sheets
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
- CWE-444Inconsistent Interpretation of HTTP Requests (HTTP Request Smuggling) (opens in a new tab)
Base weaknessOWASP Top 10 A06:2025: Insecure Design (opens in a new tab)
The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.
Implementation
Use a web server that employs a strict HTTP parsing procedure, such as Apache.
Implementation
Use only SSL communication.
Implementation
Terminate the client session after each request.
- OWASP Cheat Sheets
- OWASP ASVS 4.0.3
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
- CWE-601URL Redirection to Untrusted Site (Open Redirect) (opens in a new tab)
Base weaknessLikelihood of exploit: LowOWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a redirect.
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.
Architecture and Design
Use an intermediate disclaimer page that provides the user with a clear warning that they are leaving the current site. Implement a long timeout before the redirect occurs, or force the user to click on the link. Be careful to avoid XSS problems (CWE-79) when generating the disclaimer page.
Architecture and Design · Enforcement by Conversion
When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs.
- OWASP Cheat Sheets
- OWASP ASVS 4.0.3
- Attack patterns
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
- CWE-303Incorrect Implementation of Authentication Algorithm (opens in a new tab)
Base weaknessOWASP Top 10 A07:2025: Authentication Failures (opens in a new tab)
The requirements for the product dictate the use of an established authentication algorithm, but the implementation of the algorithm is incorrect.
- OWASP Cheat Sheets
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
- CWE-838Inappropriate Encoding for Output Context (opens in a new tab)
Base weakness
The product uses or specifies an encoding when generating output to a downstream component, but the specified encoding is not the same as the encoding that is expected by the downstream component.
Implementation · Output Encoding
Use context-aware encoding. That is, understand which encoding is being used by the downstream component, and ensure that this encoding is used. If an encoding can be specified, do so, instead of assuming that the default encoding is the same as the default being assumed by the downstream component.
Architecture and Design · Output Encoding
Where possible, use communications protocols or data formats that provide strict boundaries between control and data. If this is not feasible, ensure that the protocols or formats allow the communicating components to explicitly state which encoding/decoding method is being used.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
- OWASP Cheat Sheets
- OWASP ASVS 4.0.3
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
- CWE-538Insertion of Sensitive Information into Externally-Accessible File or Directory (opens in a new tab)
Base weaknessOWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The product places sensitive information into files or directories that are accessible to actors who are allowed to have access to the files, but not to the sensitive information.
Architecture and Design · Operation · System Configuration
Do not expose file and directory information to the user.
- OWASP Cheat Sheets
- Attack patterns
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
- GCVE source
- db.gcve.eu
- Csaf Category
- csaf_security_advisory
- Csaf Version
- 2.0
- Publisher
- Red Hat Product Security
- Advisory ID
- RHSA-2026:26323
- Vendor Severity
- high
- CVE Count
- 9
- Additional Cves
- CVE-2026-24733, CVE-2026-24734, CVE-2026-24880, CVE-2026-25854, CVE-2026-29145, CVE-2026-34483, CVE-2026-34487, CVE-2026-34500
References
Community reviews
Related threats
- Red Hat Security Advisory: tomcat security updateHighVulnerability
- CVE-2026-24734: Org.apache.tomcat:tomcat coyote: Apache Tomcat has an Improper Input Validation vulnerabilityHighVulnerability
- CVE-2026-24734: Apache Tomcat Native · Improper Input ValidationHighVulnerability
- Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement updateMediumVulnerability
- Red Hat Security Advisory: Kiali 2.4.7 for Red Hat OpenShift Service Mesh 3.0HighVulnerability