# CVE-2026-98417: Linux kernel xfrm transport header buffer overflow in espintcp

Source: https://junglewise.ai/threats/cve-2026-98417-in-the-linux-kernel-the-following-vulnerability-has-been-resolved  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-14. Updated: 2026-10-16  
License: CC BY 4.0 with a link back

CVE-2026-98417 · Severity: info · Published 2026-10-14

The Linux kernel's IPsec encryption implementation (xfrm) handles TCP-encapsulated ESP packets but fails to validate that transport header offsets remain representable after TCP stream parsing trims the envelope. An attacker sending specially crafted ESP-in-TCP packets can trigger an integer truncation that causes packet processing to fail and generates kernel warnings, potentially creating a denial-of-service condition.

Technologies: [Linux kernel](https://junglewise.ai/threats/technologies/x-linux-kernel).

## Quick answers

**Is CVE-2026-98417 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-98417 being exploited in the wild.

**How severe is CVE-2026-98417?** Informational severity, published 14 October 2026.

**Which products and versions are affected?** Linux kernel all versions since 4.5 (when RFC 8229 espintcp support was added).

**Is there a fix for CVE-2026-98417?** A patch was published on 2026-08-29: upstream fix committed Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-98417 attacked?** It is attacked over the network, in an operating system.

**Am I affected by CVE-2026-98417?** Check whether you run Linux kernel at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability exists in net/xfrm/espintcp.c where the handle_esp() function calls skb_reset_transport_header() unconditionally without checking whether the offset can fit in the skb structure. When the TCP stream parser trims the envelope, the transport header offset may exceed the representable range, causing silent truncation and triggering the skb warning path. The fix replaces the unsafe reset with skb_reset_transport_header_careful(), which returns failure on unrepresentable offsets, allowing the packet to be dropped via the existing XFRM error handling path.

## Affected products

- Linux kernel all versions since 4.5 (when RFC 8229 espintcp support was added)

## Timeline

- 2026-10-14: disclosed
- 2026-08-29: patched: upstream fix committed

## References

- [https://git.kernel.org/stable/c/206f396f46149dc8bc4dfd2b54b9879ba3ee1d7d](https://git.kernel.org/stable/c/206f396f46149dc8bc4dfd2b54b9879ba3ee1d7d)
- [https://git.kernel.org/stable/c/327b2a457dd7d5445f7395f371f3c65de79bd5ce](https://git.kernel.org/stable/c/327b2a457dd7d5445f7395f371f3c65de79bd5ce)

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