Vulnerability-Lookup

FKIE_CVE-2021-47496

Vulnerability from fkie_nvd - Published: 2024-05-22 09:15 - Updated: 2026-08-04 10:17

Severity

9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Summary

In the Linux kernel, the following vulnerability has been resolved: net/tls: Fix flipped sign in tls_err_abort() calls sk->sk_err appears to expect a positive value, a convention that ktls doesn't always follow and that leads to memory corruption in other code. For instance, [kworker] tls_encrypt_done(..., err=<negative error from crypto request>) tls_err_abort(.., err) sk->sk_err = err; [task] splice_from_pipe_feed ... tls_sw_do_sendpage if (sk->sk_err) { ret = -sk->sk_err; // ret is positive splice_from_pipe_feed (continued) ret = actor(...) // ret is still positive and interpreted as bytes // written, resulting in underflow of buf->len and // sd->len, leading to huge buf->offset and bogus // addresses computed in later calls to actor() Fix all tls_err_abort() callers to pass a negative error code consistently and centralize the error-prone sign flip there, throwing in a warning to catch future misuse and uninlining the function so it really does only warn once.

References

URL	Tags
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/da353fac65fede6b8b4cfe207f0d9408e3121105	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/e0cfd5159f314d6b304d030363650b06a2299cbb	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/e41473543f75f7dbc5d605007e6f883f1bd13b9a	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/f3dec7e7ace38224f82cf83f0049159d067c2e19	Patch
af854a3a-2127-422b-91ae-364da2661108	https://git.kernel.org/stable/c/da353fac65fede6b8b4cfe207f0d9408e3121105	Patch
af854a3a-2127-422b-91ae-364da2661108	https://git.kernel.org/stable/c/e0cfd5159f314d6b304d030363650b06a2299cbb	Patch
af854a3a-2127-422b-91ae-364da2661108	https://git.kernel.org/stable/c/e41473543f75f7dbc5d605007e6f883f1bd13b9a	Patch
af854a3a-2127-422b-91ae-364da2661108	https://git.kernel.org/stable/c/f3dec7e7ace38224f82cf83f0049159d067c2e19	Patch

Impacted products

Vendor	Product	Version
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	5.15
linux	linux_kernel	5.15
linux	linux_kernel	5.15
linux	linux_kernel	5.15
linux	linux_kernel	5.15
linux	linux_kernel	5.15
linux	linux_kernel	5.15

JSON

To clipboard

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      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/tls: Fix flipped sign in tls_err_abort() calls\n\nsk-\u003esk_err appears to expect a positive value, a convention that ktls\ndoesn\u0027t always follow and that leads to memory corruption in other code.\nFor instance,\n\n    [kworker]\n    tls_encrypt_done(..., err=\u003cnegative error from crypto request\u003e)\n      tls_err_abort(.., err)\n        sk-\u003esk_err = err;\n\n    [task]\n    splice_from_pipe_feed\n      ...\n        tls_sw_do_sendpage\n          if (sk-\u003esk_err) {\n            ret = -sk-\u003esk_err;  // ret is positive\n\n    splice_from_pipe_feed (continued)\n      ret = actor(...)  // ret is still positive and interpreted as bytes\n                        // written, resulting in underflow of buf-\u003elen and\n                        // sd-\u003elen, leading to huge buf-\u003eoffset and bogus\n                        // addresses computed in later calls to actor()\n\nFix all tls_err_abort() callers to pass a negative error code\nconsistently and centralize the error-prone sign flip there, throwing in\na warning to catch future misuse and uninlining the function so it\nreally does only warn once."
    },
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      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: net/tls: corrige las llamadas invertidas de tls_err_abort() sk-\u0026gt;sk_err parece esperar un valor positivo, una convenci\u00f3n que ktls no siempre sigue y que conduce a da\u00f1os en la memoria en otro c\u00f3digo. Por ejemplo, [kworker] tls_encrypt_done(..., err=) tls_err_abort(.., err) sk-\u0026gt;sk_err = err; [tarea] splice_from_pipe_feed ... tls_sw_do_sendpage if (sk-\u0026gt;sk_err) { ret = -sk-\u0026gt;sk_err; // ret es positivo splice_from_pipe_feed (continuaci\u00f3n) ret = actor(...) // ret sigue siendo positivo y se interpreta como bytes // escritos, lo que resulta en un desbordamiento insuficiente de buf-\u0026gt;len y // sd-\u0026gt;len, lo que genera enormes buf-\u0026gt;offset y bogus // direcciones calculadas en llamadas posteriores a actor(). Repare todas las llamadas tls_err_abort() para que pasen un c\u00f3digo de error negativo de manera consistente y centralice el cambio de se\u00f1al propenso a errores all\u00ed, lanzando una advertencia para detectar futuros usos indebidos y eliminaci\u00f3n de l\u00edneas. la funci\u00f3n por lo que realmente solo advierte una vez."
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  "lastModified": "2026-08-04T10:17:05.910",
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}

CVE-2021-47496 (GCVE-0-2021-47496)

Vulnerability from cvelistv5 – Published: 2024-05-22 08:19 – Updated: 2026-08-05 08:48

Title

net/tls: Fix flipped sign in tls_err_abort() calls

Summary

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: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2024-09-10 15:35 UTC

Assigner

Linux CNA under the mitre root

CNA scorecard D 53/100 over 7018 records in the last 180 days details

References

4 references

URL	Tags
https://git.kernel.org/stable/c/e0cfd5159f314d6b3…
https://git.kernel.org/stable/c/f3dec7e7ace38224f…
https://git.kernel.org/stable/c/e41473543f75f7dbc…
https://git.kernel.org/stable/c/da353fac65fede6b8…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: c46234ebb4d1eee5e09819f49169e51cfc6eb909 , < e0cfd5159f314d6b304d030363650b06a2299cbb (git) Affected: c46234ebb4d1eee5e09819f49169e51cfc6eb909 , < f3dec7e7ace38224f82cf83f0049159d067c2e19 (git) Affected: c46234ebb4d1eee5e09819f49169e51cfc6eb909 , < e41473543f75f7dbc5d605007e6f883f1bd13b9a (git) Affected: c46234ebb4d1eee5e09819f49169e51cfc6eb909 , < da353fac65fede6b8b4cfe207f0d9408e3121105 (git)
Linux	Linux	Affected: 4.17 Unaffected: 0 , < 4.17 (semver) Unaffected: 5.4.157 , ≤ 5.4.* (semver) Unaffected: 5.10.77 , ≤ 5.10.* (semver) Unaffected: 5.14.16 , ≤ 5.14.* (semver) Unaffected: 5.15 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

To clipboard

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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.14.16",
                  "versionStartIncluding": "4.17",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15",
                  "versionStartIncluding": "4.17",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/tls: Fix flipped sign in tls_err_abort() calls\n\nsk-\u003esk_err appears to expect a positive value, a convention that ktls\ndoesn\u0027t always follow and that leads to memory corruption in other code.\nFor instance,\n\n    [kworker]\n    tls_encrypt_done(..., err=\u003cnegative error from crypto request\u003e)\n      tls_err_abort(.., err)\n        sk-\u003esk_err = err;\n\n    [task]\n    splice_from_pipe_feed\n      ...\n        tls_sw_do_sendpage\n          if (sk-\u003esk_err) {\n            ret = -sk-\u003esk_err;  // ret is positive\n\n    splice_from_pipe_feed (continued)\n      ret = actor(...)  // ret is still positive and interpreted as bytes\n                        // written, resulting in underflow of buf-\u003elen and\n                        // sd-\u003elen, leading to huge buf-\u003eoffset and bogus\n                        // addresses computed in later calls to actor()\n\nFix all tls_err_abort() callers to pass a negative error code\nconsistently and centralize the error-prone sign flip there, throwing in\na warning to catch future misuse and uninlining the function so it\nreally does only warn once."
        }
      ],
      "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 kTLS (net/tls): a remote peer of a kTLS-offloaded service can set a negative sk_err via tls_read_size()/tls_decrypt_done() by sending a malformed TLS record, then the server\u2019s ordinary sendfile/splice TX path (tls_sw_do_sendpage) mis-handles that sk_err; per guidance, kTLS bugs driven by remote peer data are Network.\nAC:L - The attacker fully controls the malformed TLS records and can send them while the server is mid-sendfile/splice (or retry across connections); no race or memory-layout condition outside attacker influence is required for the sign-flip corruption.\nPR:N - An unauthenticated client of a public kTLS HTTPS/TLS service needs no account or capability on the host; setsockopt(TCP_ULP,\"tls\")/TLS_TX|RX also requires no capability once the tls module is loaded.\nUI:N - Exploitation needs only the attacker\u2019s TLS traffic plus the server\u2019s normal sendfile/splice response path; no separate victim user or administrator action is required.\nS:U - The pipe-buffer underflow and resulting UAF/OOB access corrupt kernel memory within the same host kernel authority and do not cross a VM, IOMMU, or sandbox boundary.\nC:H - splice_from_pipe_feed underflows buf-\u003elen and advances buf-\u003eoffset into bogus addresses, and syzbot observed a KASAN use-after-free read in __crypto_xor; that memory-corruption/UAF primitive is leverageable for arbitrary kernel disclosure.\nI:H - The same underflow drives later actor()/sendpage calls with huge offsets into reclaimed or adjacent memory, yielding OOB write and UAF write primitives that can be escalated to control-flow hijack.\nA:H - The resulting use-after-free and out-of-bounds accesses reliably oops/panic the kernel (as in the syzbot KASAN report), fully disrupting availability."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T08:48:05.957Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/e0cfd5159f314d6b304d030363650b06a2299cbb"
        },
        {
          "url": "https://git.kernel.org/stable/c/f3dec7e7ace38224f82cf83f0049159d067c2e19"
        },
        {
          "url": "https://git.kernel.org/stable/c/e41473543f75f7dbc5d605007e6f883f1bd13b9a"
        },
        {
          "url": "https://git.kernel.org/stable/c/da353fac65fede6b8b4cfe207f0d9408e3121105"
        }
      ],
      "title": "net/tls: Fix flipped sign in tls_err_abort() calls",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2021-47496",
    "datePublished": "2024-05-22T08:19:43.489Z",
    "dateReserved": "2024-05-22T06:20:56.202Z",
    "dateUpdated": "2026-08-05T08:48:05.957Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

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

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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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.

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