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CVE-2026-63993— vxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu()

CVSS 9.8 · Critical EPSS 0.52% · P41

Affected Version Matrix 18

VendorProductVersion RangeStatus
LinuxLinux4cb47a8644cc9eb8ec81190a50e79e6530d0297f< 6b8bfce9d2f774d2c2243e0248e03efb99bba6c0affected
4cb47a8644cc9eb8ec81190a50e79e6530d0297f< 9257f56ac47ef1976bcd056cf986a9988eeec67aaffected
4cb47a8644cc9eb8ec81190a50e79e6530d0297f< 8d435d68d71fb875876b722f4136caf74f2f48bdaffected
4cb47a8644cc9eb8ec81190a50e79e6530d0297f< dc3bfa050f873371e745bdf478b1f5b738e5733daffected
4cb47a8644cc9eb8ec81190a50e79e6530d0297f< 609e63312c29aad18026a1d3222e123d4b6b0febaffected
4cb47a8644cc9eb8ec81190a50e79e6530d0297f< 5303925e360527243b46a440a04667826bbc72b7affected
4cb47a8644cc9eb8ec81190a50e79e6530d0297f< a493efd4336cf19122ae0e4cbb3d31b32d70deeaaffected
4cb47a8644cc9eb8ec81190a50e79e6530d0297f< 7d9ef0cb271555d8cf39fefe6c981e1493b25ecfaffected
… +10 more rows
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I. Basic Information for CVE-2026-63993

Vulnerability Information
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Vulnerability Title
vxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: vxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu() skb_tunnel_check_pmtu() can change skb->head. Reusing old_iph afer skb_tunnel_check_pmtu() can cause an UAF. Use instead ip_hdr(skb) as done in drivers/net/bareudp.c and drivers/net/geneve.c. Found by Sashiko.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/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skb_tunnel_check_pmtu()后重用缓存的ip_hdr()值，可能导致释放后重用。以下版本受到影响：5.9版本。
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 4cb47a8644cc9eb8ec81190a50e79e6530d0297f ~ 6b8bfce9d2f774d2c2243e0248e03efb99bba6c0 -
LinuxLinux 5.9 -

II. Public POCs for CVE-2026-63993

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III. Intelligence Information for CVE-2026-63993

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Patches & Fixes for CVE-2026-63993 (6)

Same Patch Batch · Linux · 2026-07-19 · 431 CVEs total

CVE-2026-6379510.0 CRITICAL9p: avoid putting oldfid in p9_client_walk() error path
CVE-2026-641229.8 CRITICALnet/mlx5e: Fix use-after-free in mlx5e_tx_reporter_timeout_recover
CVE-2026-640009.8 CRITICALnet: hsr: fix potential OOB access in supervision frame handling
CVE-2026-641509.8 CRITICALnetfilter: nft_inner: release local_lock before re-enabling softirqs
CVE-2026-639229.8 CRITICALipv6: exthdrs: refresh nh after handling HAO option
CVE-2026-639249.8 CRITICALipv6: exthdrs: refresh nh pointer after ipv6_hop_jumbo()
CVE-2026-640469.8 CRITICALnet: tls: prevent chain-after-chain in plain text SG
CVE-2026-640479.8 CRITICALnet: tls: fix off-by-one in sg_chain entry count for wrapped sk_msg ring
CVE-2026-639949.8 CRITICALtunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]()
CVE-2026-641429.8 CRITICALksmbd: close durable scavenger races against m_fp_list lookups
CVE-2026-640559.8 CRITICALnet: ethernet: cortina: Carry over frag counter
CVE-2026-640569.8 CRITICALnet: ethernet: cortina: Make RX SKB per-port
CVE-2026-641369.8 CRITICALsmb: client: protect tc_count increment in smb2_find_smb_sess_tcon_unlocked()
CVE-2026-641329.8 CRITICALipv6: ioam: refresh hdr pointer before ioam6_event()
CVE-2026-533999.8 CRITICALnfsd: release layout stid on setlease failure
CVE-2026-641259.8 CRITICALnet: bcmgenet: keep RBUF EEE/PM disabled
CVE-2026-639849.8 CRITICALipv6: rpl: fix hdrlen overflow in ipv6_rpl_srh_decompress()
CVE-2026-638009.8 CRITICALpNFS: Fix use-after-free in pnfs_update_layout()
CVE-2026-639789.8 CRITICALnet/handshake: Drain pending requests at net namespace exit
CVE-2026-638579.8 CRITICALnet: airoha: Do not read uninitialized fragment address in airoha_dev_xmit()

Showing top 20 of 431 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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