Answer in brief
CVE-2025-21629 records a Unknown severity vulnerability in net: reenable NETIF_F_IPV6_CSUM offload for BIG TCP packets. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=a84978a9cda68f0afe3f01d476c68db21526baf1 <ac9cfef69565021c9e1022a493a9c40b03e2caf9 || >=c69bc67c1cb211aa390bea6e512bb01b1241fefb <95ccf006bbc8b59044313b8c309dcf29c546abd4 || >=04c20a9356f283da623903e81e7c6d5df7e4dc3c <d3b7a9c7597b779039a51d7b34116fbe424bf2b7 || >=04c20a9356f283da623903e81e7c6d5df7e4dc3c <68e068cabd2c6c533ef934c2e5151609cf6ecc6d || bcefc3cd7f592a70fcbbbfd7ad1fbc69172ea78b || 477b35d94a21530046fe91589960732fcf2b29ed || a27a5c40ee4cbe00294e2c76160de5f2589061ba || 9f605135a5c0fe614c2b15197b9ced1e217eca59 || 705350fbd6ed4b5d89ee045fa57a0594a72b17d7 || >=6.1.116 <6.1.124 || >=6.6.60 <6.6.70 || >=4.19.323 <4.20 || >=5.4.285 <5.5 || >=5.10.229 <5.11 || >=5.15.171 <5.16 || >=6.11.7 <6.12 | ac9cfef69565021c9e1022a493a9c40b03e2caf9, 95ccf006bbc8b59044313b8c309dcf29c546abd4, d3b7a9c7597b779039a51d7b34116fbe424bf2b7, 68e068cabd2c6c533ef934c2e5151609cf6ecc6d, 6.1.124, 6.6.70, 4.20, 5.5, 5.11, 5.16, 6.12 |
| Linux/Linuxgeneric | 6.12 | Not reported |
Published upstream
Jan 15, 2025
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 5, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 5, 2026
In the Linux kernel, the following vulnerability has been resolved: net: reenable NETIF_F_IPV6_CSUM offload for BIG TCP packets The blamed commit disabled hardware offoad of IPv6 packets with extension headers on devices that advertise NETIF_F_IPV6_CSUM, based on the definition of that feature in skbuff.h: * * - %NETIF_F_IPV6_CSUM * - Driver (device) is only able to checksum plain * TCP or UDP packets over IPv6. These are specifically * unencapsulated packets of the form IPv6|TCP or * IPv6|UDP where the Next Header field in the IPv6 * header is either TCP or UDP. IPv6 extension headers * are not supported with this feature. This feature * cannot be set in features for a device with * NETIF_F_HW_CSUM also set. This feature is being * DEPRECATED (see below). The change causes skb_warn_bad_offload to fire for BIG TCP packets. [ 496.310233] WARNING: CPU: 13 PID: 23472 at net/core/dev.c:3129 skb_warn_bad_offload+0xc4/0xe0 [ 496.310297] ? skb_warn_bad_offload+0xc4/0xe0 [ 496.310300] skb_checksum_help+0x129/0x1f0 [ 496.310303] skb_csum_hwoffload_help+0x150/0x1b0 [ 496.310306] validate_xmit_skb+0x159/0x270 [ 496.310309] validate_xmit_skb_list+0x41/0x70 [ 496.310312] sch_direct_xmit+0x5c/0x250 [ 496.310317] __qdisc_run+0x388/0x620 BIG TCP introduced an IPV6_TLV_JUMBO IPv6 extension header to communicate packet length, as this is an IPv6 jumbogram. But, the feature is only enabled on devices that support BIG TCP TSO. The header is only present for PF_PACKET taps like tcpdump, and not transmitted by physical devices. For this specific case of extension headers that are not transmitted, return to the situation before the blamed commit and support hardware offload. ipv6_has_hopopt_jumbo() tests not only whether this header is present, but also that it is the only extension header before a terminal (L4) header.
Quoted source text, attributed separately from HOL analysis.
Answer in brief
CVE-2025-21629 records a Unknown severity vulnerability in net: reenable NETIF_F_IPV6_CSUM offload for BIG TCP packets. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=a84978a9cda68f0afe3f01d476c68db21526baf1 <ac9cfef69565021c9e1022a493a9c40b03e2caf9 || >=c69bc67c1cb211aa390bea6e512bb01b1241fefb <95ccf006bbc8b59044313b8c309dcf29c546abd4 || >=04c20a9356f283da623903e81e7c6d5df7e4dc3c <d3b7a9c7597b779039a51d7b34116fbe424bf2b7 || >=04c20a9356f283da623903e81e7c6d5df7e4dc3c <68e068cabd2c6c533ef934c2e5151609cf6ecc6d || bcefc3cd7f592a70fcbbbfd7ad1fbc69172ea78b || 477b35d94a21530046fe91589960732fcf2b29ed || a27a5c40ee4cbe00294e2c76160de5f2589061ba || 9f605135a5c0fe614c2b15197b9ced1e217eca59 || 705350fbd6ed4b5d89ee045fa57a0594a72b17d7 || >=6.1.116 <6.1.124 || >=6.6.60 <6.6.70 || >=4.19.323 <4.20 || >=5.4.285 <5.5 || >=5.10.229 <5.11 || >=5.15.171 <5.16 || >=6.11.7 <6.12 | ac9cfef69565021c9e1022a493a9c40b03e2caf9, 95ccf006bbc8b59044313b8c309dcf29c546abd4, d3b7a9c7597b779039a51d7b34116fbe424bf2b7, 68e068cabd2c6c533ef934c2e5151609cf6ecc6d, 6.1.124, 6.6.70, 4.20, 5.5, 5.11, 5.16, 6.12 |
| Linux/Linuxgeneric | 6.12 | Not reported |
Published upstream
Jan 15, 2025
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 5, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 5, 2026
In the Linux kernel, the following vulnerability has been resolved: net: reenable NETIF_F_IPV6_CSUM offload for BIG TCP packets The blamed commit disabled hardware offoad of IPv6 packets with extension headers on devices that advertise NETIF_F_IPV6_CSUM, based on the definition of that feature in skbuff.h: * * - %NETIF_F_IPV6_CSUM * - Driver (device) is only able to checksum plain * TCP or UDP packets over IPv6. These are specifically * unencapsulated packets of the form IPv6|TCP or * IPv6|UDP where the Next Header field in the IPv6 * header is either TCP or UDP. IPv6 extension headers * are not supported with this feature. This feature * cannot be set in features for a device with * NETIF_F_HW_CSUM also set. This feature is being * DEPRECATED (see below). The change causes skb_warn_bad_offload to fire for BIG TCP packets. [ 496.310233] WARNING: CPU: 13 PID: 23472 at net/core/dev.c:3129 skb_warn_bad_offload+0xc4/0xe0 [ 496.310297] ? skb_warn_bad_offload+0xc4/0xe0 [ 496.310300] skb_checksum_help+0x129/0x1f0 [ 496.310303] skb_csum_hwoffload_help+0x150/0x1b0 [ 496.310306] validate_xmit_skb+0x159/0x270 [ 496.310309] validate_xmit_skb_list+0x41/0x70 [ 496.310312] sch_direct_xmit+0x5c/0x250 [ 496.310317] __qdisc_run+0x388/0x620 BIG TCP introduced an IPV6_TLV_JUMBO IPv6 extension header to communicate packet length, as this is an IPv6 jumbogram. But, the feature is only enabled on devices that support BIG TCP TSO. The header is only present for PF_PACKET taps like tcpdump, and not transmitted by physical devices. For this specific case of extension headers that are not transmitted, return to the situation before the blamed commit and support hardware offload. ipv6_has_hopopt_jumbo() tests not only whether this header is present, but also that it is the only extension header before a terminal (L4) header.
Quoted source text, attributed separately from HOL analysis.