CVE-2025-37984 (GCVE-0-2025-37984)
Vulnerability from cvelistv5 – Published: 2025-05-20 17:09 – Updated: 2026-08-05 11:58
VLAI
EPSS
VEX
Title
crypto: ecdsa - Harden against integer overflows in DIV_ROUND_UP()
Summary
In the Linux kernel, the following vulnerability has been resolved:
crypto: ecdsa - Harden against integer overflows in DIV_ROUND_UP()
Herbert notes that DIV_ROUND_UP() may overflow unnecessarily if an ecdsa
implementation's ->key_size() callback returns an unusually large value.
Herbert instead suggests (for a division by 8):
X / 8 + !!(X & 7)
Based on this formula, introduce a generic DIV_ROUND_UP_POW2() macro and
use it in lieu of DIV_ROUND_UP() for ->key_size() return values.
Additionally, use the macro in ecc_digits_from_bytes(), whose "nbytes"
parameter is a ->key_size() return value in some instances, or a
user-specified ASN.1 length in the case of ecdsa_get_signature_rs().
Severity
Assigner
References
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
55779f26eab9af12474a447001bd17070f055712 , < f02f0218be412cff1c844addf58e002071be298b
(git)
Affected: c6ab5c915da460c0397960af3c308386c3f3247b , < f2133b849ff273abddb6da622daddd8f6f6fa448 (git) Affected: c6ab5c915da460c0397960af3c308386c3f3247b , < 921b8167f10708e38080f84e195cdc68a7a561f1 (git) Affected: c6ab5c915da460c0397960af3c308386c3f3247b , < b16510a530d1e6ab9683f04f8fb34f2e0f538275 (git) Affected: 6.6.70 , < 6.6.99 (semver) |
guessed | |
| Linux | Linux |
Affected:
6.10
Unaffected: 0 , < 6.10 (semver) Unaffected: 6.6.99 , ≤ 6.6.* (semver) Unaffected: 6.12.39 , ≤ 6.12.* (semver) Unaffected: 6.14.5 , ≤ 6.14.* (semver) Unaffected: 6.15 , ≤ * (original_commit_for_fix) |
guessed |
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}
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"value": "AV:L - The affected code is the in-kernel ECDSA signature-verification path, entered from userspace via `add_key(\"asymmetric\", ...)`/`keyctl(KEYCTL_PKEY_VERIFY)` or local X.509/PKCS#7 verification. No in-kernel network consumer (ksmbd, nfsd, TLS, Bluetooth) performs ECDSA certificate verification, so the flaw is only reachable through local syscalls.\nAC:H - The `DIV_ROUND_UP()` wrap requires a value above `UINT_MAX - 7`, but every in-tree caller bounds its input \u2014 `ecdsa_get_signature_rs()` rejects `vlen \u003e ndigits*8 + 1`, the ASN.1 decoder caps `vlen` at the buffer length, and `ecdsa_key_size()` is fixed at \u226466 bytes by the curve\u0027s `nbits`. Triggering it depends on an ECDSA implementation whose `-\u003ekey_size()` callback reports an ~4 GB key, a precondition entirely outside the attacker\u0027s control and absent from any standard configuration.\nPR:L - The verification path is reachable by any unprivileged local user, who may add a crafted self-signed X.509 certificate to their own session keyring and then submit arbitrary signature blobs via `KEYCTL_PKEY_VERIFY`; no capability or namespace privilege is required.\nUI:N - The attacker drives the entire sequence through its own `add_key`/`keyctl` syscalls with attacker-supplied key and signature data; no victim action or cooperating process is needed.\nS:U - The resulting corruption is confined to kernel memory within the same kernel that runs the flawed code; no VM, hypervisor, IOMMU, or sandbox boundary is crossed.\nC:H - An underflowed `ndigits` sends `ecc_swap_digits()` iterating up to `0xFFFFFFFF` digits, reading and writing far outside the `ecdsa_raw_sig`/`pub_key` buffers, and the converted digits feed back into signature verification \u2014 an unbounded out-of-bounds access that could expose adjacent kernel memory.\nI:H - `out[--ndigits]` with `ndigits` wrapping to `0xFFFFFFFF` is a wild store roughly 32 GB past the destination buffer, followed by a multi-billion-iteration out-of-bounds write loop \u2014 an out-of-bounds write primitive that scores High.\nA:H - The runaway `ecc_swap_digits()` loop writes over arbitrary kernel memory and will immediately fault or panic the machine, and the corrupted crypto state renders the affected path unusable."
}
]
}
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"url": "https://msrc.microsoft.com/csaf/vex/2025/msrc_cve-2025-37984.json",
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncrypto: ecdsa - Harden against integer overflows in DIV_ROUND_UP()\n\nHerbert notes that DIV_ROUND_UP() may overflow unnecessarily if an ecdsa\nimplementation\u0027s -\u003ekey_size() callback returns an unusually large value.\nHerbert instead suggests (for a division by 8):\n\n X / 8 + !!(X \u0026 7)\n\nBased on this formula, introduce a generic DIV_ROUND_UP_POW2() macro and\nuse it in lieu of DIV_ROUND_UP() for -\u003ekey_size() return values.\n\nAdditionally, use the macro in ecc_digits_from_bytes(), whose \"nbytes\"\nparameter is a -\u003ekey_size() return value in some instances, or a\nuser-specified ASN.1 length in the case of ecdsa_get_signature_rs()."
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"value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: crypto: ecdsa - Protecci\u00f3n contra desbordamientos de enteros en DIV_ROUND_UP(). Herbert se\u00f1ala que DIV_ROUND_UP() puede desbordarse innecesariamente si la funci\u00f3n de retorno -\u0026gt;key_size() de una implementaci\u00f3n de ecdsa devuelve un valor inusualmente grande. En su lugar, Herbert sugiere (para una divisi\u00f3n entre 8): X / 8 + !!(X y 7). Con base en esta f\u00f3rmula, introduzca una macro gen\u00e9rica DIV_ROUND_UP_POW2() y \u00fasela en lugar de DIV_ROUND_UP() para los valores de retorno de -\u0026gt;key_size(). Adem\u00e1s, utilice la macro en ecc_digits_from_bytes(), cuyo par\u00e1metro \"nbytes\" es un valor de retorno de -\u0026gt;key_size() en algunos casos, o una longitud ASN.1 especificada por el usuario en el caso de ecdsa_get_signature_rs()."
}
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"initial_release_date": "2025-05-20T00:00:00+00:00",
"product_status:known_affected": "232",
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"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: crypto: ecdsa - Harden against integer overflows in DIV_ROUND_UP()",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-37984.json",
"version": "3"
}
}
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
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.
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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.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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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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