SB2026090319 - Multiple vulnerabilities in IBM webMethods API Management
Published: September 3, 2026
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 20 vulnerabilities.
1) Uncontrolled Memory Allocation (CVE-ID: CVE-2026-45416)
CWE-ID: CWE-789 - Uncontrolled Memory Allocation
CVSSv4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to uncontrolled memory allocation in SslClientHelloHandler.decode() when processing a TLS ClientHello that does not fit in the first record. A remote attacker can send a specially crafted ClientHello with a large handshake length to cause a denial of service.
The issue is exposed by the commonly used SniHandler and AbstractSniHandler constructors because they disable the client hello length guard and do not schedule a handshake timeout.
2) Inconsistent interpretation of HTTP requests (CVE-ID: CVE-2026-42584)
CWE-ID: CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request Smuggling')
CVSSv4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to disrupt HTTP parsing integrity and availability on the connection.
The vulnerability exists due to inconsistent interpretation of HTTP responses in HttpClientCodec when processing pipelined HTTP/1.1 responses that include a 1xx response before a GET response body and a subsequent HEAD response. A remote attacker can send a specially crafted sequence of HTTP responses to disrupt HTTP parsing integrity and availability on the connection.
Exploitation requires HTTP/1.1 pipelining, a HEAD request in the pipeline, and a server response sequence that includes a 1xx response.
3) Null Byte Interaction Error (Poison Null Byte) (CVE-ID: CVE-2026-42579)
CWE-ID: CWE-626 - Null Byte Interaction Error (Poison Null Byte)
CVSSv4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to bypass domain validation and poison DNS caches.
The vulnerability exists due to improper input validation in io.netty.handler.codec.dns.DnsCodecUtil encodeDomainName() when encoding user-influenced domain names. A remote attacker can supply a crafted domain name containing null bytes, overlength labels, or empty labels to bypass domain validation and poison DNS caches.
The issue affects the encoder path and relies on applications using user-influenced hostnames to construct DNS queries.
4) Generation of Predictable Numbers or Identifiers (CVE-ID: CVE-2026-45673)
CWE-ID: CWE-340 - Generation of Predictable Numbers or Identifiers
CVSSv4: 8.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to poison the DNS cache.
The vulnerability exists due to generation of predictable numbers or identifiers in the Netty DNS resolver when generating DNS transaction IDs and using the default static UDP source port for DNS queries. A remote attacker can spoof DNS responses to poison the DNS cache.
Successful exploitation may cause downstream applications to connect to malicious IP addresses, enabling traffic interception or machine-in-the-middle attacks.
5) Insufficient verification of data authenticity (CVE-ID: CVE-2026-45674)
CWE-ID: CWE-345 - Insufficient Verification of Data Authenticity
CVSSv4: 9.1 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to poison the DNS cache.
The vulnerability exists due to insufficient verification of data authenticity in DnsResolveContext buildAliasMap when processing CNAME records in DNS responses. A remote attacker can send a malicious DNS response containing out-of-bailiwick CNAME records to poison the DNS cache.
Any application using Netty's DNS resolver is impacted.
6) Insufficient verification of data authenticity (CVE-ID: CVE-2026-47691)
CWE-ID: CWE-345 - Insufficient Verification of Data Authenticity
CVSSv4: 9.1 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to poison the DNS cache.
The vulnerability exists due to insufficient verification of data authenticity in the DnsResolveContext.AuthoritativeNameServerList handling of NS records when processing DNS responses containing NS records in the AUTHORITY section and A records in the ADDITIONAL section. A remote attacker can provide crafted DNS records to poison the DNS cache.
Exploitation requires control of an authoritative name server for a subdomain, and the poisoned cache can affect future resolutions under the parent domain.
7) Resource exhaustion (CVE-ID: CVE-2026-47244)
CWE-ID: CWE-400 - Resource exhaustion
CVSSv4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to uncontrolled resource consumption in the HTTP/2 stream management logic when handling HTTP/2 connections without an explicitly configured concurrent stream limit. A remote attacker can open a large number of streams over a single TCP connection to cause a denial of service.
The issue occurs when the application does not explicitly configure a maximum concurrent streams setting.
8) Missing Release of Resource after Effective Lifetime (CVE-ID: CVE-2026-48043)
CWE-ID: CWE-772 - Missing Release of Resource after Effective Lifetime
CVSSv4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to a reference-count leak in DelegatingDecompressorFrameListener when processing HTTP/2 frames that cause the flow-controller to throw. A remote attacker can send crafted frames to cause a denial of service.
The issue may exhaust memory and eventually take down the JVM due to an out-of-memory error.
9) Incorrect Comparison (CVE-ID: CVE-2026-44249)
CWE-ID: CWE-697 - Incorrect Comparison
CVSSv4: 9.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to bypass IPv6 subnet access controls.
The vulnerability exists due to incorrect comparison in IpSubnetFilterRule.compareTo() when evaluating IPv6 subnet rules. A remote attacker can use a valid public IP address to bypass IPv6 subnet access controls.
The issue is caused by applying a bitwise AND operation to the configured networkAddress instead of the subnetMask.
10) Inconsistent interpretation of HTTP requests (CVE-ID: CVE-2026-42585)
CWE-ID: CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request Smuggling')
CVSSv4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to inject arbitrary HTTP requests.
The vulnerability exists due to inconsistent interpretation of HTTP requests in HttpRequestDecoder when parsing malformed Transfer-Encoding headers. A remote attacker can send a specially crafted HTTP request with a malformed "Transfer-Encoding: chunked, identity" header to inject arbitrary HTTP requests.
Exploitation is possible in deployments where a proxy forwards such malformed requests to Netty instead of rejecting them.
11) Allocation of Resources Without Limits or Throttling (CVE-ID: CVE-2026-42583)
CWE-ID: CWE-770 - Allocation of Resources Without Limits or Throttling
CVSSv4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to uncontrolled resource consumption in io.netty.handler.codec.compression.Lz4FrameDecoder#decode when processing crafted LZ4 frames. A remote attacker can send a specially crafted compressed frame header and payload to cause a denial of service.
On the compressed path, header fields are trusted for sizing, allowing a small request to force allocation of a much larger ByteBuf.
12) Resource exhaustion (CVE-ID: CVE-2026-42587)
CWE-ID: CWE-400 - Resource exhaustion
CVSSv4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to uncontrolled resource consumption in HttpContentDecompressor and DelegatingDecompressorFrameListener when processing compressed HTTP request bodies with Content-Encoding set to br, zstd, or snappy. A remote attacker can send a specially crafted compressed payload to cause a denial of service.
The configured maxAllocation limit is enforced for gzip and deflate, but is silently ignored for brotli, zstd, and snappy. The issue affects both HTTP/1.1 and HTTP/2 handling.
13) HTTP response splitting (CVE-ID: CVE-2026-42578)
CWE-ID: CWE-113 - Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Response Splitting')
CVSSv4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to inject arbitrary HTTP headers into CONNECT proxy requests.
The vulnerability exists due to improper neutralization of CRLF sequences in HTTP headers in io.netty.handler.proxy.HttpProxyHandler newInitialMessage() when handling user-influenced outbound headers. A remote attacker can supply crafted header values containing CRLF sequences to inject arbitrary HTTP headers into CONNECT proxy requests.
Exploitation requires an application to use HttpProxyHandler with user-influenced outboundHeaders without performing its own CRLF sanitization.
14) CRLF injection (CVE-ID: CVE-2026-41417)
CWE-ID: CWE-93 - Improper Neutralization of CRLF Sequences ('CRLF Injection')
CVSSv4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to inject additional HTTP or RTSP requests.
The vulnerability exists due to improper neutralization of CRLF sequences in DefaultHttpRequest.setUri() and DefaultFullHttpRequest.setUri() when encoding attacker-controlled URIs into request lines through HttpRequestEncoder or RtspEncoder. A remote attacker can supply a specially crafted URI containing CRLF sequences to inject additional HTTP or RTSP requests.
Exploitation requires an application to create the request object first, later modify it through setUri(), and then serialize it with HttpRequestEncoder or RtspEncoder.
15) Missing Release of Resource after Effective Lifetime (CVE-ID: CVE-2026-45536)
CWE-ID: CWE-772 - Missing Release of Resource after Effective Lifetime
CVSSv4: 4.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to improper resource shutdown in netty_unix_socket_recvFd when receiving SCM_RIGHTS control messages containing two file descriptors over a unix domain socket. A remote attacker can send a specially crafted message to cause a denial of service.
The issue is reachable via Epoll/KQueue DomainSocketChannel only when the application enables DomainSocketReadMode.FILE_DESCRIPTORS.
16) Inconsistent interpretation of HTTP requests (CVE-ID: CVE-2026-50020)
CWE-ID: CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request Smuggling')
CVSSv4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to smuggle HTTP requests.
The vulnerability exists due to inconsistent interpretation of HTTP requests in HttpObjectDecoder when parsing requests with non-CRLF control characters before the request-line. A remote attacker can send a specially crafted request to smuggle HTTP requests.
The issue can cause request-boundary confusion when a front-end component interprets the prepended bytes differently in pipelined or multiplexed transports.
17) Resource exhaustion (CVE-ID: CVE-2026-50560)
CWE-ID: CWE-400 - Resource exhaustion
CVSSv4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to improper handling of SETTINGS_MAX_HEADER_LIST_SIZE in the netty http/2 codec when processing http/2 requests with a client-supplied maximum header list size setting. A remote attacker can send specially crafted http/2 requests to cause a denial of service.
The issue is similar in effect to the HTTP/2 Rapid Reset attack but has a different on-the-wire signature.
18) Inconsistent interpretation of HTTP requests (CVE-ID: CVE-2026-42580)
CWE-ID: CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request Smuggling')
CVSSv4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to inject arbitrary HTTP requests.
The vulnerability exists due to inconsistent interpretation of HTTP requests in io.netty.handler.codec.http.HttpObjectDecoder#getChunkSize when parsing chunked HTTP requests. A remote attacker can send a specially crafted chunked request to inject arbitrary HTTP requests.
19) Inconsistent interpretation of HTTP requests (CVE-ID: CVE-2026-42581)
CWE-ID: CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request Smuggling')
CVSSv4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to perform request smuggling.
The vulnerability exists due to improper input validation in HttpObjectDecoder when processing HTTP/1.0 requests containing both Transfer-Encoding: chunked and Content-Length headers. A remote attacker can send a specially crafted HTTP/1.0 request to perform request smuggling.
Exploitation requires Netty to be deployed behind a downstream proxy or handler that trusts Content-Length over Transfer-Encoding.
20) Improper Certificate Validation (CVE-ID: CVE-2026-50010)
CWE-ID: CWE-295 - Improper Certificate Validation
CVSSv4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to disclose sensitive information.
The vulnerability exists due to improper certificate validation in X509TrustManagerWrapper within netty-handler when establishing client TLS connections with a user-supplied plain X509TrustManager. A remote attacker can present a certificate for an unexpected hostname to disclose sensitive information.
The issue occurs because hostname verification is not performed in this configuration, even when HTTPS endpoint identification is expected by default.
Remediation
Install update from vendor's website.