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CVE-2026-31503— udp: Fix wildcard bind conflict check when using hash2

EPSS 0.01% · P2
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I. Basic Information for CVE-2026-31503

Vulnerability Information
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Vulnerability Title
udp: Fix wildcard bind conflict check when using hash2
Source: NVD (National Vulnerability Database)
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: udp: Fix wildcard bind conflict check when using hash2 When binding a udp_sock to a local address and port, UDP uses two hashes (udptable->hash and udptable->hash2) for collision detection. The current code switches to "hash2" when hslot->count > 10. "hash2" is keyed by local address and local port. "hash" is keyed by local port only. The issue can be shown in the following bind sequence (pseudo code): bind(fd1, "[fd00::1]:8888") bind(fd2, "[fd00::2]:8888") bind(fd3, "[fd00::3]:8888") bind(fd4, "[fd00::4]:8888") bind(fd5, "[fd00::5]:8888") bind(fd6, "[fd00::6]:8888") bind(fd7, "[fd00::7]:8888") bind(fd8, "[fd00::8]:8888") bind(fd9, "[fd00::9]:8888") bind(fd10, "[fd00::10]:8888") /* Correctly return -EADDRINUSE because "hash" is used * instead of "hash2". udp_lib_lport_inuse() detects the * conflict. */ bind(fail_fd, "[::]:8888") /* After one more socket is bound to "[fd00::11]:8888", * hslot->count exceeds 10 and "hash2" is used instead. */ bind(fd11, "[fd00::11]:8888") bind(fail_fd, "[::]:8888") /* succeeds unexpectedly */ The same issue applies to the IPv4 wildcard address "0.0.0.0" and the IPv4-mapped wildcard address "::ffff:0.0.0.0". For example, if there are existing sockets bound to "192.168.1.[1-11]:8888", then binding "0.0.0.0:8888" or "[::ffff:0.0.0.0]:8888" can also miss the conflict when hslot->count > 10. TCP inet_csk_get_port() already has the correct check in inet_use_bhash2_on_bind(). Rename it to inet_use_hash2_on_bind() and move it to inet_hashtables.h so udp.c can reuse it in this fix.
Source: NVD (National Vulnerability Database)
CVSS Information
N/A
Source: NVD (National Vulnerability Database)
Vulnerability Type
N/A
Source: NVD (National Vulnerability Database)
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于UDP通配符绑定冲突检查在使用hash2时存在逻辑错误，可能导致地址冲突检测失败。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

VendorProductAffected VersionsCPESubscribe
LinuxLinux 30fff9231fad757c061285e347b33c5149c2c2e4 ~ d6ace0dbcbb7fd285738bb87b42b71b01858c952 -
LinuxLinux 2.6.33 -

II. Public POCs for CVE-2026-31503

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III. Intelligence Information for CVE-2026-31503

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Same Patch Batch · Linux · 2026-04-22 · 100 CVEs total

CVE-2026-314639.8 CRITICALiomap: fix invalid folio access when i_blkbits differs from I/O granularity
CVE-2026-314449.8 CRITICALksmbd: fix use-after-free and NULL deref in smb_grant_oplock()
CVE-2026-315019.8 CRITICALnet: ti: icssg-prueth: fix use-after-free of CPPI descriptor in RX path
CVE-2026-314369.8 CRITICALdmaengine: idxd: fix possible wrong descriptor completion in llist_abort_desc()
CVE-2026-314789.8 CRITICALksmbd: replace hardcoded hdr2_len with offsetof() in smb2_calc_max_out_buf_len()
CVE-2026-314489.4 CRITICALext4: avoid infinite loops caused by residual data
CVE-2026-314328.8 HIGHksmbd: fix OOB write in QUERY_INFO for compound requests
CVE-2026-314338.8 HIGHksmbd: fix potencial OOB in get_file_all_info() for compound requests
CVE-2026-314508.8 HIGHext4: publish jinode after initialization
CVE-2026-314358.8 HIGHnetfs: Fix read abandonment during retry
CVE-2026-314768.2 HIGHksmbd: do not expire session on binding failure
CVE-2026-314648.1 HIGHscsi: ibmvfc: Fix OOB access in ibmvfc_discover_targets_done()
CVE-2026-315138.1 HIGHBluetooth: L2CAP: Fix stack-out-of-bounds read in l2cap_ecred_conn_req
CVE-2026-315047.8 HIGHnet: fix fanout UAF in packet_release() via NETDEV_UP race
CVE-2026-314497.8 HIGHext4: validate p_idx bounds in ext4_ext_correct_indexes
CVE-2026-315027.8 HIGHteam: fix header_ops type confusion with non-Ethernet ports
CVE-2026-314317.8 HIGHcrypto: algif_aead - Revert to operating out-of-place
CVE-2026-314887.8 HIGHdrm/amd/display: Do not skip unrelated mode changes in DSC validation
CVE-2026-314907.8 HIGHdrm/xe/pf: Fix use-after-free in migration restore
CVE-2026-314547.8 HIGHxfs: save ailp before dropping the AIL lock in push callbacks

Showing top 20 of 100 CVEs. View all on vendor page → →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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