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CVE-2026-46193

xfrm: ah: account for ESN high bits in async callbacks

published

In the Linux kernel, the following vulnerability has been resolved: xfrm: ah: account for ESN high bits in async callbacks AH allocates its temporary auth/ICV layout differently when ESN is enabled: the async ahash setup appends a 4-byte seqhi slot before the ICV or auth_data area, but the async completion callbacks still reconstruct the temporary layout as if seqhi were absent. With an async AH implementation selected, that makes AH copy or compare the wrong bytes on both the IPv4 and IPv6 paths. In UML repro on IPv4 AH with ESN and forced async hmac(sha1), ping fails with 100% packet loss, and the callback logs show the pre-fix drift: ah4 output_done: esn=1 err=0 icv_off=20 expected_off=24 ah4 input_done: esn=1 auth_off=20 expected_auth_off=24 icv_off=32 expected_icv_off=36 Reconstruct the callback-side layout the same way the setup path built it by skipping the ESN seqhi slot before locating the saved auth_data or ICV. Per RFC 4302, the ESN high-order 32 bits participate in the AH ICV computation, so the async callbacks must account for the seqhi slot. Post-fix, the same IPv4 AH+ESN+forced-async-hmac(sha1) UML repro shows the corrected offset (ah4 output_done: esn=1 err=0 icv_off=24 expected_off=24) and ping succeeds; net/ipv4/ah4.o and net/ipv6/ah6.o build clean at W=1. IPv6 AH+ESN was not exercised at runtime, and the change has not been tested against a real async hardware AH engine.

Technical severity5.5 mediumCVSS 3.1 · NVD: [email protected]
Published2026-05-28Source updated 2026-11-10
Collected2026-11-103 attributed sources

Fixes and workarounds

Fix

The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.

Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

Fix

The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.

Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

Fix

The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.

Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

Fix

The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.

Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

Fix

The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.

Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

Affected products and versions

ProductVersionsAuthority
Linux
Linux 		≥ d4d573d0334d07341beffdcf97e2b85d3955d8ae; < ec406c26c97594124e79d14516b729a8d5dced62 (affected, git)
≥ d4d573d0334d07341beffdcf97e2b85d3955d8ae; < 1dae77078ceb4bab833f7a4935f05c5b8c97b9ba (affected, git)
≥ d4d573d0334d07341beffdcf97e2b85d3955d8ae; < 0555d4f526232b3c9e3afbcd490c0c0793aefec6 (affected, git)
≥ d4d573d0334d07341beffdcf97e2b85d3955d8ae; < 729899a2aa8bda7844be0cdcd3b470f11b912eda (affected, git)
≥ d4d573d0334d07341beffdcf97e2b85d3955d8ae; < 7db99a09b3bc87268287bc7ab5f2e7f382b5ad87 (affected, git)
≥ d4d573d0334d07341beffdcf97e2b85d3955d8ae; < 2ffaa7a94f9a4d22724364a1821735a0231d9f8d (affected, git)
≥ d4d573d0334d07341beffdcf97e2b85d3955d8ae; < ec54093e6a8f87e800bb6aa15eb7fc1e33faa524 (affected, git)
Other versions: unaffected 		CNA: Linux
Linux
Linux 		3.15 (affected)
≥ 0; < 3.15 (unaffected, semver)
≥ 5.15.210; ≤ 5.15.* (unaffected, semver)
≥ 6.1.176; ≤ 6.1.* (unaffected, semver)
≥ 6.6.140; ≤ 6.6.* (unaffected, semver)
≥ 6.12.88; ≤ 6.12.* (unaffected, semver)
≥ 6.18.30; ≤ 6.18.* (unaffected, semver)
≥ 7.0.7; ≤ 7.0.* (unaffected, semver)
≥ 7.1; ≤ * (unaffected, original_commit_for_fix)
Other versions: affected 		CNA: Linux
SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0)
Siemens 		≥ V3.1.6; < * (affected, custom)
Other versions: unknown 		ADP: siemens-SADP
SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0)
Siemens 		≥ V3.1.7; < * (affected, custom)
Other versions: unknown 		ADP: siemens-SADP
SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0)
Siemens 		≥ V3.1.6; < * (affected, custom)
Other versions: unknown 		ADP: siemens-SADP
SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0)
Siemens 		≥ V3.1.7; < * (affected, custom)
Other versions: unknown 		ADP: siemens-SADP
SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0)
Siemens 		≥ V3.1.6; < * (affected, custom)
Other versions: unknown 		ADP: siemens-SADP
SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0)
Siemens 		≥ V3.1.7; < * (affected, custom)
Other versions: unknown 		ADP: siemens-SADP
SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0)
Siemens 		≥ V3.1.6; < * (affected, custom)
Other versions: unknown 		ADP: siemens-SADP
SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0)
Siemens 		≥ V3.1.7; < * (affected, custom)
Other versions: unknown 		ADP: siemens-SADP
SIMATIC S7-1500 TM MFP - GNU/Linux subsystem
Siemens 		≥ 0; < * (affected, custom)
Other versions: unknown 		ADP: siemens-SADP
SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0)
Siemens 		≥ V3.1.6; < * (affected, custom)
Other versions: unknown 		ADP: siemens-SADP
SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0)
Siemens 		≥ V3.1.7; < * (affected, custom)
Other versions: unknown 		ADP: siemens-SADP

Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.

NVD applicability configurations (1)

These expressions retain AND/OR operators, negation, and required environmental products. A listed product is not sufficient to establish exposure when additional conditions apply.

[
  {
    "negate": false,
    "nodes": [
      {
        "cpeMatch": [
          {
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionEndExcluding": "6.6.140",
            "versionStartIncluding": "3.15",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionEndExcluding": "6.12.88",
            "versionStartIncluding": "6.7",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionEndExcluding": "6.18.30",
            "versionStartIncluding": "6.13",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionEndExcluding": "7.0.7",
            "versionStartIncluding": "6.19",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:*",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:*",
            "vulnerable": true
          }
        ],
        "negate": false,
        "operator": "OR"
      }
    ],
    "operator": "OR"
  }
]

CVSS assessments

Version / scoreVectorAuthority
3.1 / 5.5
medium		 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HNVD: [email protected]

Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

References

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