CVE-2025-40176 (GCVE-0-2025-40176)

Vulnerability from cvelistv5 – Published: 2025-11-12 10:53 – Updated: 2026-10-15 22:02
VLAI
Title
tls: wait for pending async decryptions if tls_strp_msg_hold fails
Summary
In the Linux kernel, the following vulnerability has been resolved: tls: wait for pending async decryptions if tls_strp_msg_hold fails Async decryption calls tls_strp_msg_hold to create a clone of the input skb to hold references to the memory it uses. If we fail to allocate that clone, proceeding with async decryption can lead to various issues (UAF on the skb, writing into userspace memory after the recv() call has returned). In this case, wait for all pending decryption requests.
Severity
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
SSVC
Exploitation: none Automatable: yes Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-15 21:57 UTC
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 7033 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 84c61fe1a75b4255df1e1e7c054c9e6d048da417 , < 9f83fd0c179e0f458e824e417f9d5ad53443f685 (git)
Affected: 84c61fe1a75b4255df1e1e7c054c9e6d048da417 , < c61d4368197d65c4809d9271f3b85325a600586a (git)
Affected: 84c61fe1a75b4255df1e1e7c054c9e6d048da417 , < 39dec4ea3daf77f684308576baf483b55ca7f160 (git)
Affected: 84c61fe1a75b4255df1e1e7c054c9e6d048da417 , < 4fc109d0ab196bd943b7451276690fb6bb48c2e0 (git)
Affected: 84c61fe1a75b4255df1e1e7c054c9e6d048da417 , < b8a6ff84abbcbbc445463de58704686011edc8e1 (git)
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Linux Linux Affected: 6.0
Unaffected: 0 , < 6.0 (semver)
Unaffected: 6.1.158 , ≤ 6.1.* (semver)
Unaffected: 6.6.114 , ≤ 6.6.* (semver)
Unaffected: 6.12.55 , ≤ 6.12.* (semver)
Unaffected: 6.17.5 , ≤ 6.17.* (semver)
Unaffected: 6.18 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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                  "version": "84c61fe1a75b4255df1e1e7c054c9e6d048da417",
                  "versionType": "git"
                }
              ]
            },
            {
              "defaultStatus": "affected",
              "product": "Linux",
              "programFiles": [
                "net/tls/tls_sw.c"
              ],
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "vendor": "Linux",
              "versions": [
                {
                  "status": "affected",
                  "version": "6.0"
                },
                {
                  "lessThan": "6.0",
                  "status": "unaffected",
                  "version": "0",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "6.1.*",
                  "status": "unaffected",
                  "version": "6.1.158",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "6.6.*",
                  "status": "unaffected",
                  "version": "6.6.114",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "6.12.*",
                  "status": "unaffected",
                  "version": "6.12.55",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "6.17.*",
                  "status": "unaffected",
                  "version": "6.17.5",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "*",
                  "status": "unaffected",
                  "version": "6.18",
                  "versionType": "original_commit_for_fix"
                }
              ]
            }
          ],
          "cpeApplicability": [
            {
              "nodes": [
                {
                  "cpeMatch": [
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "6.1.158",
                      "versionStartIncluding": "6.0",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "6.6.114",
                      "versionStartIncluding": "6.0",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "6.12.55",
                      "versionStartIncluding": "6.0",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "6.17.5",
                      "versionStartIncluding": "6.0",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "6.18",
                      "versionStartIncluding": "6.0",
                      "vulnerable": true
                    }
                  ],
                  "negate": false,
                  "operator": "OR"
                }
              ]
            }
          ],
          "descriptions": [
            {
              "lang": "en",
              "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntls: wait for pending async decryptions if tls_strp_msg_hold fails\n\nAsync decryption calls tls_strp_msg_hold to create a clone of the\ninput skb to hold references to the memory it uses. If we fail to\nallocate that clone, proceeding with async decryption can lead to\nvarious issues (UAF on the skb, writing into userspace memory after\nthe recv() call has returned).\n\nIn this case, wait for all pending decryption requests."
            }
          ],
          "metrics": [
            {
              "cvssV3_1": {
                "baseScore": 9.8,
                "baseSeverity": "CRITICAL",
                "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
                "version": "3.1"
              },
              "scenarios": [
                {
                  "lang": "en",
                  "value": "AV:N - The bug is in the kTLS software receive path (net/tls/tls_sw.c) processing TLS records supplied by the remote peer, with the record stream, sizes and record types fully controlled by that peer. Per kernel scoring guidance, kTLS bugs triggered by remote TLS peer data are Network.\nAC:L - Once the skb_clone()/alloc_skb() allocation fails, the outcome is deterministic, and a remote peer can drive the memory pressure that induces it by opening many connections and queueing large record backlogs (trivially so under memcg-constrained containers). The remaining conditions \u2014 TLS 1.2 plus an async-capable AEAD \u2014 are the default on affected stable kernels since x86 AES-NI GCM registers through the SIMD wrapper with CRYPTO_ALG_ASYNC.\nPR:N - The attacker is the remote TLS peer of an already-established kTLS connection and needs no privileges or account on the target system. The vulnerable code runs as part of normal server-side record processing.\nUI:N - No victim action beyond the server\u0027s ordinary recv()/recvmsg() loop, which runs automatically as part of serving the connection. No configuration change, file open, or mount is required.\nS:U - The corruption is confined to kernel memory and the receiving process\u0027s own address space within the same security authority. No VM, IOMMU, or sandbox boundary is crossed.\nC:H - The live strparser anchor skb is queued on async_hold and later freed by __skb_queue_purge() while strp-\u003eanchor still references it, giving a use-after-free on an skbuff that an attacker can reclaim with sprayed network data; the in-flight AEAD also reads input skb memory whose references were dropped. Per guidance, use-after-free is High.\nI:H - The UAF/double-free on the anchor skb yields a heap write primitive after slab reclaim, and the crypto engine additionally writes attacker-chosen plaintext into the pinned user pages after recv() has already returned, corrupting whatever the application has since placed in that buffer. Per guidance, use-after-free is High.\nA:H - The freed anchor skb remains reachable from softirq context via tls_strp_data_ready and is freed a second time by tls_strp_anchor_free() on close, causing oops/panic or slab corruption. Any use-after-free or double-free is High availability impact."
                }
              ]
            }
          ],
          "providerMetadata": {
            "dateUpdated": "2026-08-05T12:08:21.202Z",
            "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "shortName": "Linux"
          },
          "references": [
            {
              "url": "https://git.kernel.org/stable/c/9f83fd0c179e0f458e824e417f9d5ad53443f685"
            },
            {
              "url": "https://git.kernel.org/stable/c/c61d4368197d65c4809d9271f3b85325a600586a"
            },
            {
              "url": "https://git.kernel.org/stable/c/39dec4ea3daf77f684308576baf483b55ca7f160"
            },
            {
              "url": "https://git.kernel.org/stable/c/4fc109d0ab196bd943b7451276690fb6bb48c2e0"
            },
            {
              "url": "https://git.kernel.org/stable/c/b8a6ff84abbcbbc445463de58704686011edc8e1"
            }
          ],
          "title": "tls: wait for pending async decryptions if tls_strp_msg_hold fails",
          "x_generator": {
            "engine": "bippy-1.2.0"
          }
        }
      },
      "cveMetadata": {
        "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "assignerShortName": "Linux",
        "cveId": "CVE-2025-40176",
        "datePublished": "2025-11-12T10:53:50.443Z",
        "dateReserved": "2025-04-16T07:20:57.177Z",
        "dateUpdated": "2026-10-15T22:02:39.716Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



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Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

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How durations are calculated

Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

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    Related by attack behaviour

    Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.