CVE-2025-21629: net: reenable NETIF_F_IPV6_CSUM offload for BIG TCP packets
CSIRTS triage
- What
- IPv6 checksum offload for BIG TCP packets was re-enabled to prevent denial of service.
- Who is affected
- Systems using IPv6 checksum offload with Big TCP packet handling.
- Urgency
- Moderately urgent as the issue can cause network availability problems.
- Action
- Apply the kernel patch that re-enables NETIF_F_IPV6_CSUM offload for BIG TCP packets.
AI-assisted analysis generated from the source advisory — verify against the original.
⚡ Watch Linux Kernel
Get an email when a new Linux Kernel advisory drops — max one per day, one-click unsubscribe.
Details
Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-21629
Exploitation outlook
EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.
- Low exploitation riskCVE-2025-216290.41% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 34% of all EPSS-scored CVEs.
Referenced CVEs
| CVE | CSIRTS overview | External |
|---|---|---|
| CVE-2025-21629 | coverage & exploitation status | NVD · CVE.org |
Recent advisories for net
A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.
- medium[UPDATE] [medium] Golang Go-Module (Net, Image, Crypto): Multiple Vulnerabilitiescert-bund · 2026-08-07
- unknownCVE-2026-64587: In the Linux kernel, the following vulnerability has been resolved: net: ethernet: arc: emac: …nvd · 2026-08-06
- mediumCVE-2025-71095: net: stmmac: fix the crash issue for zero copy XDP_TX actionmsrc · 2026-08-06
- highCVE-2025-39905: net: phylink: add lock for serializing concurrent pl->phydev writes with resolvermsrc · 2026-08-06
- highCVE-2026-45940: net: stmmac: fix oops when split header is enabledmsrc · 2026-08-06
- mediumCVE-2025-38717: net: kcm: Fix race condition in kcm_unattach()msrc · 2026-08-06
More from Microsoft Security Response Center
- highCVE-2025-40776: Birthday Attack against Resolvers supporting ECS2026-08-06
- lowCVE-2026-3632: Libsoup: libsoup: http smuggling and server-side request forgery via malformed hostnames2026-08-06
- unknownCVE-2026-58039: CVE-2026-580392026-08-06
- unknownCVE-2026-19023: HDF5 h5dump Untrusted Pointer Dereference in Binary Output of Variable-Length String Datasets2026-08-06
- mediumCVE-2026-23247: tcp: secure_seq: add back ports to TS offset2026-08-06