CVE-2026-23240 | tls: Fix race condition in tls_sw_cancel_work_tx()

In the Linux kernel, the following vulnerability has been resolved: tls: Fix race condition in tls_sw_cancel_work_tx() This issue was discovered during a code audit. After cancel_delayed_work_sync() is called from tls_sk_proto_close(), tx_work_handler() can still be scheduled from paths such as the Delayed ACK handler or ksoftirqd. As a result, the tx_work_handler() worker may dereference a freed TLS object. The following is a simple race scenario: cpu0 cpu1 tls_sk_proto_close() tls_sw_cancel_work_tx() tls_write_space() tls_sw_write_space() if (!test_and_set_bit(BIT_TX_SCHEDULED, &tx_ctx->tx_bitmask)) set_bit(BIT_TX_SCHEDULED, &ctx->tx_bitmask); cancel_delayed_work_sync(&ctx->tx_work.work); schedule_delayed_work(&tx_ctx->tx_work.work, 0); To prevent this race condition, cancel_delayed_work_sync() is replaced with disable_delayed_work_sync().

Published: 2026-03-10 Last update: 2026-05-20 Assigner: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-23240 is rated Moderate Risk (45.6/100): CVSS Critical severity, with low exploitation likelihood (EPSS 0.06%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-23240

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-04-03 0.02% 0.06% +0.04%
2 2026-03-11 — 0.02% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-23240

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 416baaa9-dc9f-4396-8d5f-8c081fb06d67

Weakness enumeration for CVE-2026-23240

GitHub Security Advisory for CVE-2026-23240

GHSA-c96v-vvf3-2p7r · Severity: critical — In the Linux kernel, the following vulnerability has been resolved: tls: Fix race condition in...

OS Trackers for CVE-2026-23240

vendor priority summary link
debian not yet assigned CVE-2026-23240 not yet assigned priority: Debian including 1 source packages (linux), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 3, open 2. https://security-tracker.debian.org/tracker/CVE-2026-23240
redhat medium — https://access.redhat.com/security/cve/CVE-2026-23240
suse medium CVE-2026-23240 severity moderate: SUSE including 18 source package names (cluster-md-kmp-default, dlm-kmp-default, …), 50 product×package rows across 10 product lines (SUSE Linux Enterprise Live Patching 12 SP5, SUSE Linux Enterprise Micro 5.0, … (10 product lines)): Known Not Affected 46, Fixed 4. https://www.suse.com/security/cve/CVE-2026-23240/
ubuntu medium CVE-2026-23240 medium priority: Ubuntu including 157 source packages (linux, linux-allwinner-5.19, …), 1256 status rows across 8 suites (bionic, focal, jammy, noble, questing, trusty, upstream, xenial): DNE 871, ignored 169, needed 109, released 83, not-affected 24. https://ubuntu.com/security/CVE-2026-23240

Affected software / configurations for CVE-2026-23240

Vendor Product Version Raw CPE
linux linux_kernel >= 5.3.1, < 6.12.75 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.13, < 6.18.16 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.19, < 6.19.6 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel 5.3 cpe:2.3:o:linux:linux_kernel:5.3:-:*:*:*:*:*:*
linux linux_kernel 5.3 cpe:2.3:o:linux:linux_kernel:5.3:rc4:*:*:*:*:*:*
linux linux_kernel 5.3 cpe:2.3:o:linux:linux_kernel:5.3:rc5:*:*:*:*:*:*
linux linux_kernel 5.3 cpe:2.3:o:linux:linux_kernel:5.3:rc6:*:*:*:*:*:*
linux linux_kernel 5.3 cpe:2.3:o:linux:linux_kernel:5.3:rc7:*:*:*:*:*:*
linux linux_kernel 5.3 cpe:2.3:o:linux:linux_kernel:5.3:rc8:*:*:*:*:*:*
linux linux_kernel 7.0 cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*

References for CVE-2026-23240

cvelogic Threat Intelligence