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CVE-2026-63925— macsec: fix replay protection at XPN lower-PN wrap

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会开源的一款操作系统内核。 Linux kernel存在安全漏洞，该漏洞源于macsec_post_decrypt()函数在XPN lower-PN环绕时未正确处理pn等于U32_MAX的情况，导致pn + 1溢出并绕过重放保护，攻击者可以捕获并无限重放带有pn == 0xFFFFFFFF的合法帧。

CVSS 8.1 · High EPSS 0.40% · P33

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux a21ecf0e033807b976967286e6c392f48ee2049f< dd7306779c6ce1238f4cdc34f3c1f2246b854457 affected
a21ecf0e033807b976967286e6c392f48ee2049f< d15130461df388136b62a7b0ce9f66e7e2fa9ff1 affected
a21ecf0e033807b976967286e6c392f48ee2049f< 23c0e230eab397d7f68be2538790ac41d3bb91fd affected
a21ecf0e033807b976967286e6c392f48ee2049f< 679e13a65e68a67c8b3c0467c02ee89157ec6f0f affected
a21ecf0e033807b976967286e6c392f48ee2049f< 79495a1b0944fe31ffd54b54b00211b493590d62 affected
a21ecf0e033807b976967286e6c392f48ee2049f< 6d00f5c7e5ff7ec4795b7f5f8ed88bd346641652 affected
a21ecf0e033807b976967286e6c392f48ee2049f< d55acbe577db892b60547b6ef1c020b359331a6d affected
a21ecf0e033807b976967286e6c392f48ee2049f< e68842b3356471ba56c882209f324613dac47f64 affected
… +10 more rows
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I. Basic Information for CVE-2026-63925

Vulnerability Information
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Vulnerability Title
macsec: fix replay protection at XPN lower-PN wrap
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: macsec: fix replay protection at XPN lower-PN wrap In macsec_post_decrypt(), when pn is U32_MAX, pn + 1 overflows u32 to 0 and the first branch never fires. If next_pn_halves.lower is also in the upper half, pn_same_half(pn, lower) is true and the XPN else-if does not fire either, leaving next_pn_halves unchanged. An attacker that captures the legitimate frame carrying pn == 0xFFFFFFFF on an XPN association can then replay it indefinitely, since lowest_pn never rises above the captured pn and macsec_decrypt() reconstructs the same IV. Extend the XPN else-if to also fire when pn + 1 wraps to 0, so receipt of pn == U32_MAX advances next_pn_halves to (upper + 1, 0).
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会开源的一款操作系统内核。 Linux kernel存在安全漏洞，该漏洞源于macsec_post_decrypt()函数在XPN lower-PN环绕时未正确处理pn等于U32_MAX的情况，导致pn + 1溢出并绕过重放保护，攻击者可以捕获并无限重放带有pn == 0xFFFFFFFF的合法帧。
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

Vendor Product Affected Versions CPE Subscribe
Linux Linux a21ecf0e033807b976967286e6c392f48ee2049f ~ dd7306779c6ce1238f4cdc34f3c1f2246b854457 -
Linux Linux 5.7 -

II. Public POCs for CVE-2026-63925

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III. Intelligence Information for CVE-2026-63925

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Patches & Fixes for CVE-2026-63925 (7)

Same Patch Batch · Linux · 2026-07-19 · 429 CVEs total

CVE-2026-63795 10.0 CRITICAL 9p: avoid putting oldfid in p9_client_walk() error path
CVE-2026-64016 9.8 CRITICAL ksmbd: fix durable reconnect error path file lifetime
CVE-2026-53398 9.8 CRITICAL NFSD: Fix SECINFO_NO_NAME decode error cleanup
CVE-2026-64136 9.8 CRITICAL smb: client: protect tc_count increment in smb2_find_smb_sess_tcon_unlocked()
CVE-2026-64037 9.8 CRITICAL wifi: iwlwifi: mld: fix TSO segmentation explosion when AMSDU is disabled
CVE-2026-64035 9.8 CRITICAL igc: set tx buffer type for SMD frames
CVE-2026-63800 9.8 CRITICAL pNFS: Fix use-after-free in pnfs_update_layout()
CVE-2026-64033 9.8 CRITICAL RDMA/rtrs: Fix use-after-free in path file creation cleanup
CVE-2026-64142 9.8 CRITICAL ksmbd: close durable scavenger races against m_fp_list lookups
CVE-2026-63808 9.8 CRITICAL exfat: fix potential use-after-free in exfat_find_dir_entry()
CVE-2026-63888 9.8 CRITICAL scsi: target: iscsi: Fix CRC overread and double-free in iscsit_handle_text_cmd()
CVE-2026-64025 9.8 CRITICAL bpf, skmsg: fix verdict sk_data_ready racing with ktls rx
CVE-2026-63887 9.8 CRITICAL scsi: target: iscsi: Bound iscsi_encode_text_output() appends to rsp_buf
CVE-2026-64089 9.8 CRITICAL batman-adv: tt: fix negative last_changeset_len
CVE-2026-63886 9.8 CRITICAL scsi: target: iscsi: Validate CHAP_R length before base64 decode
CVE-2026-64122 9.8 CRITICAL net/mlx5e: Fix use-after-free in mlx5e_tx_reporter_timeout_recover
CVE-2026-64102 9.8 CRITICAL RDMA/siw: Reject MPA FPDU length underflow before signed receive math
CVE-2026-63984 9.8 CRITICAL ipv6: rpl: fix hdrlen overflow in ipv6_rpl_srh_decompress()
CVE-2026-63979 9.8 CRITICAL net/handshake: hand off the pinned file reference to accept_doit
CVE-2026-63993 9.8 CRITICAL vxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu()

Showing top 20 of 429 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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