CVE-2019-25005
Counter overflow in chacha20
An issue was discovered in the chacha20 crate before 0.2.3 for Rust. A ChaCha20 counter overflow makes it easier for attackers to determine plaintext.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- None
- Availability
- None
Exploit likelihood
What each source reports
NVD Score used
An issue was discovered in the chacha20 crate before 0.2.3 for Rust. A ChaCha20 counter overflow makes it easier for attackers to determine plaintext.
- Record
CVE-2019-25005- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N - CVSS 2.0
- 5.0 Medium
AV:N/AC:L/Au:N/C:P/I:N/A:N - Weakness
- CWE-190
- Updated
- 2026-11-02
CVE List No score
An issue was discovered in the chacha20 crate before 0.2.3 for Rust. A ChaCha20 counter overflow makes it easier for attackers to determine plaintext.
- Record
CVE-2019-25005- Updated
- 2026-11-02
EUVDEUVD-2021-1765 No score
An issue was discovered in the chacha20 crate before 0.2.3 for Rust. A ChaCha20 counter overflow makes it easier for attackers to determine plaintext.
- Record
EUVD-2021-1765- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-j2r6-2m5c-vgh5
Counter overflow in chacha20
An issue was discovered in the chacha20 crate before 0.2.3 for Rust. A ChaCha20 counter overflow makes it easier for attackers to determine plaintext.
- Record
GHSA-j2r6-2m5c-vgh5- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N - Weakness
- CWE-190
- Updated
- 2026-11-02
OSVGHSA-j2r6-2m5c-vgh5
Counter overflow in chacha20
An issue was discovered in the chacha20 crate before 0.2.3 for Rust. A ChaCha20 counter overflow makes it easier for attackers to determine plaintext.
- Record
GHSA-j2r6-2m5c-vgh5- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N - Weakness
- CWE-190
- Updated
- 2026-11-02
OSVRUSTSEC-2019-0029
ChaCha20 counter overflow can expose repetitions in the keystream
The ChaCha20 stream cipher can produce a maximum of 2^32 blocks (~256GB)
before the 32-bit counter overflows. Releases of the chacha20 crate prior
to v0.2.3 allow generating keystreams larger than this, including seeking
past the limit. When this occurs, the keystream is duplicated, with failure
modes similar to nonce reuse (i.e. exposure of the XOR of two plaintexts).
The v0.2.3 release now panics in this event, rather than exposing the duplicated keystream. Note this is a "hot fix" solution to the problem and future releases will pursue returning an error in this case.
Users of the chacha20poly1305 crate are unaffected by this as this crate
properly asserts the length of the plaintext is less than the maximum allowed
(P_MAX as described in RFC 8439 Section 2.8).
- Record
RUSTSEC-2019-0029- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N - Updated
- 2026-11-02
Affected products
Affected packages
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2019-25005 is a high vulnerability (CVSS 7.5) in Chacha20 Project Chacha20, published October 22, 2019. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.32%, the 71st percentile. Fixed in chacha20 0.2.3.